To be truthful, I memed and posted a bit quick, as I'm looking at it there is no reference to a particular group of leftists, but protesters today are all leftists, therefore anyone looking at the meme knows I'm referring to current event asswipe protesters.
If they had masks on it'd be a shoe in for antifa, but thier angry faces and the signs they're holding lets everyone in on thier fascistic, lockstep demands of everyone, demands made in the name of "tolerance" of course, so it's not a huge leap for people to fill in that particular blank:
Hillary voters, still pissed off about 2016. From there, it could be any generic leftist who demand you don't have an independent thought other than what the party platform tells you, in the name of diversity of opinion, and tolerance.