I don't think it actually would make them happy or happier
This group has a problem with the content existing at all, self moderation tools have been suggested and implemented in other contexts, and in a limited degree on twitter today (mute and block) and that is not seen as "good enough"
The group that opposes free speech does not just want to be in a self guided safe space no they want to ensure no one can says things they have deemed hate speech or misinformation. Many of this group also want to go further and punish people outside of the platform they spoke incorrectly on
So to imply self moderation tools is the solution completely misunderstands the goals of the "avoid-harassment side" which is to control and narrow the Overton window
Yes, they're zealots. It's similar to how religious zealots refused to simply "change the channel" when they found something objectionable.