They're trolling by insulting people based on their messed up imagination of what somebody might be, or might think, that has nothing to do with the topic.
Just as political parties have varied members and they're not all the same, trolls come in different varieties.
"It is easier to fool someone, than to convince them they have been fooled."
For those that don't get it, it means that people need to be more careful, and do good due diligence...