If you call that revisionist history, then what do you call the fact that immediately after his first stroke, his PR team (heavily associated with Scientology) tried to claim that he merely suffered from an episode of "high blood pressure and exhaustion" only for the truth to be revealed 6 months later that it was indeed a stroke?

He gave up his control and that is on him and only him.

Like I said in my initial comment, he did choose to join them on his own free will, so we're in agreement there. But I also said that his last few years (i.e. everything post-'06 stroke) was controlled by the Scientologists when he was not in a position to tell them to fuck off, even if he wanted to (which admittedly, would be debatable). They saw an opening and ran with it, that was my point; you're claiming that he willingly gave up all his autonomy and I simply don't agree with that. Or at least he was not mentally sound enough to be able to do so, just like how putting rohypnol in someone's drink doesn't equal "yes means yes"

Blaming a MLM scheme hiding as a religion for a death is pointless since there was nothing that prevented him from breaking away as others have done.

Simply because some have broken ties with the cult doesn't mean that all members have the same options to break away as the fortunate few. ESPECIALLY if the majority of the people around him, those controlling his perception of the outside world, were actively trying to keep him in. A core fundamental philosophy from Hubbard himself was to draw in as many celebrities as possible for the express purpose of using them to prostelytize his works. Plus, and let's be frank here, Hayes was not in the prime of his life anymore; he wasn't so far gone as to be labeled "decrepit" or "on death's door" at the time of his death, but even if he was living completely alone and didn't have Church members constantly surrounding/influencing him, it's hard to say whether or not he would've had the opportunity to leave.

I mean, come on man, the Church literally encourages members to "disconnect" with all aspects and people of their former lives who are not themselves members. It's also pretty common knowledge that anyone who leaves is not only shunned by the organization (which, if the disconnection was effective) had been the basis for their entire lives for a long time by that point; they're also contantly harassed, stalked, and occasionally threatened directly from still-current members. Even if those actions aren't technically ordered to be done by the leaders, they still happen regularly without any condemnation or comment from the top brass. And this isn't even getting into the multiple deaths they are DIRECTLY responsible for, or the fact that Shelly Miscavige (the wife of the current head of rhe Church) has not publicly been seen ANYWHERE by ANYONE since 2007. Or Operation Snow White in the 1970s where up to 5,000 individual members worked to get jobs in various branches of the US (and Canadian) government for the explicit and stated purpose of covering up Hubbard's and the Church's more controversial practices. If they can manage to pull all that shit off and still somehow get away without the most minor of consequences, I'm sure they can manage to draft the equivalent of a Termination of Emploment, convince a perpetually confused Isaac into signing it, and then sending it off to the South Park offices.

tl;dr You're forgetting the most important single line from that episode of South Park:

We shouldn't be mad at Chef. We should be mad at that fruity little club for scrambling his brains