He guys. I remember weeks or months ago people having already posted in the comment sections of The Underground Bunker that they're securing Marty's stuff, for example to the internet archive.

I've read that more than once, and Marty has become increasingly crazy and evidence of a payoff has hardened ... so suppose someone actually did copy his posts by now.
That at some point
some of Marty's blog posts could vanish, is but a reasonable assumption, given the circumstances.
However, this is why I
personally don't think that Marty will ever delete
all or
most of his blog posts (pure speculation ofcourse): he is very narcissistic and
essentially convinced that his shit is the hottest shit ever. One can see that not only in his recent reprehensible actions but ever since in his pretentious philosophical ramblings and his pseudointellectual style. His blog posts (and books etc)
are very important to him - regardless of whether meanwhile he might have changed his opinions about some of these topics. To him, it's all "brilliant stuff" and "documentation of his genius" and "incredibly helpful for every advice seeking reader".

I suspect he would not have made any deal that demands him to delete his blog. Single posts maybe, but never all of them. He's way too vain for that.
Again, all speculation ofcourse, and I'm curious as to whether I'll be wrong.