The IAS does a great deal more than "nothing".
The IAS funds all sorts of capers to "defend the Scientology religion".
It funds nasty intelligence operations, overwhelming lawsuits, private investigators, PR publications, and on and on.
I suppose that the IAS is the MONEY BANK for OSA and all of its many secretive shenanigans. The IAS provides the "war chest" for the Church of Scientology, and it is always at war with someone.
The IAS provides Miscavige with the means to conduct whatever surreptitious activities he desires.
In the past, and possible even today, the CIA used drug money to fund various covert operations around the world. The Church of Scientology uses IAS Money to fund its nasty operations.
And, to many over-indoctrinated Scientologists, that is
totally okay with them. To such imbeciles it is quite all right to lie, cheat, deceive, misrepresent, and act in any way to HARM any of Scientology's "enemies". The IAS provides the funds that enable them to work overtime trying to do so.