Sealioning is a Gamergate tactic, so it's quite possible he's one of those disruptive children, and that's where he learned it from. He's certainly doing it regularly and systematically and by the book, as if it's a job he's been trained to do, he has a checklist of talking points and techniques, and is being paid for his time, number of posts, and number of words.

https://knowyourmeme.com/memes/sea-lioning

Another tactic you can see him practicing, which we're all familiar with coming out of the White House, is psychological projection. Trolls like misterman are fully aware they're sealioning, know all the terminology because they study and emulate it, and they love to throw around and misuse terms like that themselves, to attack other sincere people for doing what they're actually maliciously doing themselves, to make it seem like it's just "both sides", which it's not.

It's not just an internet thing. Here's an example of how racists sealion and project in real life:

https://medium.com/@codeGrit/a-story-about-sealions-gamergat...