General Moderation Topic

What does it mean when a username appears in a quote and isn’t clickable (and the user doesn’t seem to have a user page), and when you try to unroll the quoted text and you see a garbage can / jump to the post and go somewhere random in the topic? I assume the garbage can and limbo jump means the quoted post was deleted. Is the missing user a moderation action? Or something else? I didn’t think it was possible to outright delete an account (and thus orphan all of a user’s post quotes).

I admit this is morbid curiosity. I see a lot of clearly troll-like posts from one B_D_Newsome over in the guns and stale bad arguments topic, and said user and their posts don’t seem to exist anymore, but I don’t see any report of moderation actions over here and I’m, well, morbidly curious.