It doesn't matter what a commenter on HN has. A rare ironic case where the original comment isn't ad-hominem, but the dinging rebuttal is.
This is ad hominem. The link provided only supports the accusation with previous accusations.
Both were ad-hominem. The first one also suffers from a pompous bias: What does it even matter if the submission is not peer-reviewed? It could have been posted on a blog! It is dropping little seeds of doubt, to weaken and attack something you don't want to attack directly:
"A warning to everyone that the linked website does not adhere to Wikipedia guidelines for being a credible source."
Expect better. If you demand peer-review, then review the contents as a peer! You have the opportunity to get what you want, instead of needlessly attacking a fellow scientist' credibility.
Surely a distinction can be made between attacking someone's character and attacking their claim to authority. Within every scientific paper there's an implicit claim to authority and here the track record has weight alongside whatever qualifications they may have.
https://en.m.wikipedia.org/wiki/Ad_hominem
It appears that the original comment was valid ad hominem, but still ad hominem.