This may not even be Maoist moderators. A comment like that is little too obviously horrible. What I think happened is that fascists have appropriated a political sub-Reddit in order to smear that political movement. Something similar happened to the "/r/Feminism" sub-Reddit. I suspect Reddit's CEO Jack Dorsey, who is a racist and fascist, deliberately hands control of any sub-Reddit he hates over to provocateur moderators.
Or maybe this just always ends up happening to leftist sub-Reddits for some other reason.