1. In my opinion, Hubbard did not use rhetoric, he used Crowleyian subtle communication, which I talked about in my blog post on Magick and the tech.
There are only two ways to sway others according to Plato. One is force, the other persuasion. Persuasion involves rhetoric....however the lines can blur between persuasion and force....so when does something cease to be rhetoric and persuasion and become control, force, hypnosis?
I don't appeal to any ethos acquired by association with David Mayo and my training under him since I have not talked to him since I was over the rainbow studying under him. For all I know he wants nothing to do with me, and therefore that appeal to authority would fail since he would discredit me. At least, we have had no connection in decades and I have no idea what he now believes about beings, souls, technology, or anything else, including CoS. I hope that any credibility I have is based on what I say and not who I was although I realize it all somehow ends up factoring in. Since I don't use any of their tech and find it all spurious, I would probably fail to be a poster child for the FZ or indies. On one hand I think they are in their rights to pursue their religious freedom as codified in U.S. law and I think that even the CoS has no authority there.
A question then arises for me of religious freedom for those departing, who are told they are SPs even though in my opinion they are asserting their own religious freedom, that is the freedom to believe different spiritual concepts than those officially sanctioned by CoS. Since I am closer in thinking to those who reject all of it, not just the CoS but all LRH "tech", I am baffled at all those who having left still think there is something to save there. However, I respect anyone's right to do what is best for themselves, which is more than CoS grants to each of those departing its ranks.
2. I use logic, which the way I define it is simply a way of organizing thought. Scientology has a logic, CoS has a bureaucratic logic, FZ has a logic, Islam has a logic, carpentry has a logic, there are countless logics and countless philosophies and countless systems, existing now and historically. The question then is to understand what logics are in play, what are the stakes. The logic I have used here is a non-Scilon logic, a sort of wog Western philosophy logic coupled with my admitted Christian beliefs which I generally don't talk about since I find those off-topic to the forum. They come into play only as an admission of my bias, i.e., that my logic is colored by a Christian ethos....
When using logic, I admit I have a large toolkit of logics to employ, not always apparent. I try to avoid attack and ad hominem, which generally the Church uses. The reason is that ad hominems are historically understood to be last resort arguments made when there are no substantive issues to pursue. That is, if you really have no case, try to discredit a person. This form of logic should never be used if at all possible to avoid since it has such a bad backfire effect. So much so that legal dictionaries make this very point. Only discredit a witness if you have no case.
Generally a lot of other tools can be used so why bother with that form of logic, the weakest type really, which borders on force and has little to do with rhetoric or persuasion.
There is very little logical in CoS and its techs so it is easy to find lines on which to deconstruct the assertions of being scientific and so on. Keep in mind that an ad hominem has to do with attacking specific persons. Criticizing a philosophy on specific grounds is completely different. Appalling actions taken by CoS add to the problems with their system because it reveals a purpose and effect which are not helpful to human advancement, their largest claim.
3. Pathos and emotions. Even though I use logic, I am much more interested in the consequences of pathos, the negative effects caused by certain beliefs and values. Logic always has a limit. Logics can be evil. The Nazis were logical and scientific in some of their endeavors and yet they were evil and their logical system of values harmed human beings. Their ultimate fate was to be understood as a malevolent force in history, a force to be studied for the purpose of avoiding those mistakes in future.
Logic often serves practical purposes. Its an ability human beings have to 'make sense of' things. This gift becomes scientific or becomes practical and has its basis in our ability to find reasons, to be reasoning beings.
But logic needs to have a benevolent loving master, logic must be at the service of doing good and being good, not at the service of being the strongest will, of doing what thou wilt or, to use the Scilon lingo, of being the 'total cause'.
What makes us human is a mixture of being logical / understanding of reasons and our vulnerability / authenticity /heart in relation to life and others. Our logic is fine in the context of heart. When logic becomes its own end and when it wants to control, be cause of others, of things, and when logic wants to rule itself and be in command of reality, then logic has gone off the rails. This is one reason why I think all the tech is flawed, it's a set of already confused logics mixed together with a form of selfish self-advancement. Proof of this is seen in the view of family taken by CoS. In all fascist systems, the family is the biggest impediment since it qualifies the control that the fascistic system would have over its herd.
Hubbard's nefarious 'reason' and reasoning was 'Do as thou wilt', another way to say 'be total cause'.
This topic of total cause and consciousness has been hashed over endlessly before LRH was born by philosophers, using other words. I won't repeat the stakes, the issues, the side paths and by ways of that complicated discussion. Only will close in stating that philosophy found that path to be a dead end for too many reasons to list. And that it was a path that had its birth in the death of god, that is, that at some point in the history of philosophy, during the Enlightenment period, the view of God as being at the center of philosophy faded. The new center became the I or consciousness. Hubbard's system is but another flavor at the baskin-robbins case, one of many iterations of paths consciousness, if it were a god, could take. Anyway, this is just a bit of my thinking. It's also possible I misunderstood what you were asking me, but I tried to answer anyway on some level.