Okay, breaking my rule here: yes, I am wondering that as well. Here's my assumption: the mods straight-up banned this individual's previous accounts, but shadowbanned this one instead. But shadowbanning just kills your comments automatically; in recentish times, HN has added a "vouch" feature that lets you vouch for a comment and get it un-killed. So I imagine that's what happend, which seems like a weakness in the shadowbanning feature, though maybe it's good as well, I don't know. The right way to know is to email the HN mods via the "contact" link at the bottom.