His comments seem entirely reasonable to me. Why are they all grey?

He is definitely Hellbanned. He made a poor-taste attempt at humor on a mental health post (https://news.ycombinator.com/item?id=407576) which was voted to oblivion, and every post since then is [dead]. Looks like it took him a few months to find it (I had to go back like 10 "more" clicks to get to his non-dead posts).

Account may have been hellbanned.

its a great example of the failure of the hellbanned concept. time to ditch it and stop looking like "TOTAL ASSHOLE HACKER NEWS YCOMBINATOR"?

Or are the admins/moderators really this oversensitive? Cry more. Grow up noobs.

So HN can be more like every other internet forum since Usenet in 1985 and angry repressed basement dwellers can unleash their fury anonymously to make up for the fact that they can barely look other human beings in the face?

Plenty of places to do that on the internet, I'm happy for one place enforce a higher standard.

Not using capital letters for the first word of sentences ?

Possibly. Hacker news is a rough neighborhood if you use improper grammar, have bad spelling, or make typos.