The moral principle in this case is that we don't think jail (or worse) should happen without being proven guilty. That does not mean we collectively believe all consequence requires proof of being guilty. Morals and punishment are not binary systems.
There's a point where this kind of ostracism becomes worse than jail. For many Twitch users, streaming is a substantial part of their social environment or even their full-time job. If I had to choose between a couple weeks in jail and a lifetime ban from working in my industry, or a couple weeks in jail and being banned from all my friend group chats, I'd take jail in a heartbeat.
On the other hand, one person's ostracism is another's right of association. It is just as wrong to force someone to work with a person they do not want to work with, as long as that reason is justifiable (i.e. not a protected class)
For Twitch and other corporations it seems like it's not the "right of association", but more the "sin of association" that makes them heavy handed towards individuals with banning, censoring and demonetizing:
The extreme social media dynamics somehow holds these corporations accountable for any wrongdoings someone might post on their platforms which is impossible to prevent or moderate in a timely fashion. They respond with more sophisticated and sweeping algorithms that lead to self-censorship by content creators and unexpected actions like shutting down the demoscene event a few days ago.
Well, I agree with what you're saying, although I'm not sure we're on the same page. I don't think Twitch should be forced to work with people they'd rather ban; I see some proposals in other comment threads to pass a law, and I don't support that. What I want is for Twitch to recognize that this new policy is a bad idea and voluntarily retract it.
Many of the offenses are in that category. My concern is the offenses like "violent extremism" and "membership in a known hate group", which are not generally illegal and very easy to abuse for censorious purposes. (I've seen quite a few people identify mainstream organizations as "hate groups" because of some political dispute.)
Presumption of evidence is morally important because the force of the state is ultimate: they can deprive a person of life and liberty as a consequence.
The suggestion that it is immoral for a different standard being applied to a private clubhouse is not something that was supported by the influential thinkers who gave us the former idea.
In a capitalistic society where corporations hold as much power or more than governments do in our day to day lives you surely must see how this is a moral principle that must apply to them also. There's life ruining things beyond jail such as being homeless and shunned.
