There are so many subreddits that are so ban-happy they'll ban you just for daring to participate in another subreddit that they don't like, that if one doesn't do that, I don't think it can qualify as "one of the most ban happy" ones.
So in my experience they very much did NOT become safe spaces, even when faced with every idea I could think of which could be considered solidly "left."
They also tend to speak favorably about certain U.S. Republicans whom they say are pro free-speech and when you point out they are pro banning (BDS as an example), you either get instantly blocked or they suddenly 'are tired of this conversation and no longer wish to engage'.
Oh the irony.
I'm not saying that doing the former won't get you blocked too by rightists who basically just want their own echo chambers, but the latter seems to be the default level of discourse on Twitter when talking to the "other," so if that's what you defaulted to, I'm not too surprised you were shown the door.
Still others would rather just have a place to avoid politics altogether. My main account is on phpc.social which is supposed to be a hub for the PHP community, but recently there's been an uptick of people joining (or re-activating old accounts) and posting or reposting political nonsense. Quite annoying.
I specifically joined Mastodon to escape that and to try and see what the other side is really about. There are two broad categories of 'rightists' on Mastodon - the ones who are just looking to be provocative and then there are the ones who present themselves as more serious.
The first camp are non-serious trolls seeking to enrage, so I did not engage with them. The 'serious' ones are generally posting all kinds of things incl. toots I sometimes like and agree with and so I follow some of these accounts.
The problem with the second category is that when it comes to political discussions they tend to retreat to the same level of discourse as the trolls often. For example say a discussion turns to Jeremy Corbyn; they'll refuse to look at/read anything that suggests against him being what they believe him being, (some kind of CCP agent/extremist sympathizer/left of Meo communist that would've crashed the UK economy, ironic as that may sound atm).
Everything suggesting otherwise is some kind of a leftist rag apparently, but baseless accusation pieces confirming their bias I should take as authoritative.
Not seeing a contradiction between cheering the firing of a left-leaning professor and supposedly being pro free speech or endorsing someone who is for banning BDS as being pro free speech.
It also tends to happen that if I do admit some of their points as valid, they tend to take it as some sort of a big win and basically present it as a complete win for their argument, ignoring the points I countered them on completely. Everything seems to be a contest to own me and this is with people who outside of politics seem to be posting about tech, music or whatever.
It's extremely hard for me to find any right-leaning person on there who wants to find things we agree on, exchange civil views on things we don't and basically reach out in good faith. I know people like that are out there, but it doesn't seem to me like they number many, not on Mastodon for sure.