FWIW, as far as we can tell this account was part of a long-running Microsoft astroturfing campaign. You can never be 100% sure of these things, but astroturfers, like spammers, leave trails they don't realize they're leaving.
I can see your comments on the original article fine. I do not think that you are hellbanned. If you were shadow banned, won't the comments be invisible to me?
I think HN has different kinds of "bans" and some may be temporary, but don't quote me on that. You may find that if you give it a day or two, that you will be able to post with your old account. If not, you can try emailing pg directly and plead your case to have the ban removed. No guarantees, but I've heard of other people doing that and getting things restored.
Is it an unfortunate side effect of an aggressive banning algorithm? The particular people downvoting were not 'out to get you' perhaps - just a side-effect of folks downvoting as usual to show disagreement, a valid HN behavior.
If your account had lived a little longer, others might have chimed in and restored balance. But an algorithm that works that way would leave HN open to griefers etc.