They muddy the waters. They wheedle, rules-lawyer, carve out exceptions, and talk about how important it is to have nuance in separating virtuous applications for slop from bad ones, and that focusing on the bad ones is actually very tedious and rude. We should have polite discourse about the good things about slop and stop being so mean about bad slop, which isn't even really a problem. The bad kinds of slop will be solved soon, probably, and the harms are overstated. They colonize spaces.
If moderators don't swiftly throw these slop enthusiasts out on their ass, slightly less polite ones will post slop slightly less politely. More and more of the people participating in the space will have favorable opinions toward slop, and shout down people who object to slop. In no time at all, your community is a slop bar. Who could have imagined?