I never saw any actual brigading on the sub itself. Others talk about "organizing brigades through Twitter," and I think it's kind of BS to punish people for that. Reddit doesn't get to police Twitter, and vice versa.
Never saw any actual advocacy of violence against any specific person, either. Sure, there were "kill the landlords" type jokes and memes, but the closest I think I ever saw it get to actual incitement of violence was stuff like "Kissinger needs to fucking die already," or "I would prefer that Trump exit the White House feet first, in a box." You can call that whatever you like, but it's certainly not advocating violence against anyone.
Meanwhile, there's literally a Stalin meme on the front page of r/fullcommunism that says "death to capitalism." Then, there's r/latestagecapitalism, which is a toxic shithole of a sub where you literally can't say "that idea is crazy and will never work because $REASONS," because they have a blacklist of words that are "slurs" of one sort of another that they don't publish, and which will get your post removed if you try and use them.
The mods, not the admins, made it so that only a shortlist of approved users could post content in the subreddit.
It was likely a move to push the community somewhere else.
The admins even said as much when explaining the ban.
Admins banned virtually all the mods, without warning or explanation, so the remaining mod(s) had no choice but to lock the sub.
One of the tricks leftist groups like to do is they'll brigade right-leaning subs, post a ton of "offensive" content, then before the mods can remove it, they'll screenshot it, post it up on a blog, and then alert the admins to trick them into banning the sub. That's how they got the sub quarantined.
With only one or two mods left, they couldn't properly police the sub anymore, which had close to a million subscribers and tens of thousands of active posters at any given hour. Put yourself in their shoes. If it was the choice between accept random unknown (but admin approved) users as moderators, or lock the sub, what would you do?
Of course you'd lock the sub. It was just an attempt at a soft-takeover. Better it be outright banned than lobotomized by replacing its mods with Reddit users who likely hate Trump.
Are you skeptical of the Nicene creed? If you are skeptical of the Nicene creed, does this mean you deny the existence of Christian people?
Are you skeptical of body thetans? If you are skeptical of body thetans, does this mean you deny the existence of Scientologists?
Are you skeptical of climate change? If you are skeptical of climate change, does this mean you deny the existence of climatologists?