From what I recall, based on what a Godot developer wrote at the time, nobody got banned from GitHub for "a reasonable objection". The only people who got banned from GitHub were those who posted abuse there, after a few people had gotten blocked by the Godot Twitter account
The problem here is the definition of abuse. And I don't mean to say that I'm 100% sure Godot overstepped in the github ban cases, but if they can ban people for criticizing them I wouldn't be surprised if they overstepped there too.