I feel like the word troll has lost it's meaning since sites like reddit started using it just to describe anyone with alternative views.

That is correct for a lot of words: incel, depression, cringe, mysoginy, etc.

I still use it since there's no better alternative. It still conveys the meaning.

I just think his views seem genuine and pretty much exactly in line with leftist beliefs

It's because of how he portrays his beliefs. I talked to leftists online and offline from all levels of insanity and either he's a reactionary like Hassan or a genuine troll. That's how I interpreted how he engaged with other people on the website.

He's either someone who understands their views REALLY well, much more closely than your average troll would be or someone who genuinely believes that stuff.

You're missing something. He also understands OUR views. He tries breaking them using specific words to piss us off and cause a reaction.

I would suggest reading his comment section again and coming with a new perspective. If he's a troll he will delete his account at some point.