It's also frustrating because there are people who are sincerely trying to discuss in good faith while having a different opinion, which is camouflage for the sealion trolls.

Of course, people increasingly forget about the former group completely, and react with hostility... It's understandable, but unfortunate for healthy discussion.

At least in your case, your response is to lay out robust arguments to explain your position, which is productive regardless of whether they're trolling or sincere. I've learned a great deal over the years from strangers on the internet putting a clinic on someone who may or may not have been trolling.