Okay dude, so I probably wasted more time on this than I should have, but here's what I found:
His username is fs. He always went by fs and never by swain.
A whole bunch of his posts are critiques and criticisms, but a lot of them are in the channel called "art_help," or from people specifically asking for advice or thoughts on their drawing.
The guy seems super polite and a lot of people thank him for his input (pic related).
So I decided to just look for the images that he posted, since you said he spammed them a lot.
He rarely ever posted the same image twice and I don't think he ever posted more often than that. He never posted his Adventure Time comic. He never once mentioned his patreon.
As for whining about personal matters, I didn't dig that deeply. If you remember an example, I could look that up, but I wasn't going to read through every single one of his posts.
Here's what I think is happening: I think he upset you at some point, for whatever reason. And you remember that feeling of getting angry and upset, but you don't actually remember why. So you've held on to that anger, and you've had to scrounge up justifications and excuses for it.
You oughta go searching through his post to refresh your memory of what actually bothered you. Maybe now, in retrospect, it won't be as upsetting as it was when it happened.
tl;dr I think you're remembering a lot of details incorrectly and you're angry for no reason.
If you're willing, you could tell me what your username was and I can find any interactions he had with you, and maybe find an instance of him being shitty to you.