I think the kernel of contributors with a good-faith interest in bitcoin is smaller than you think it is, but either way: if bitcoin is getting multiples of the attention that the hiring thread is, I think most reasonable HN people can agree that it's being overrepresented.
Lawyering over the site guidelines here isn't productive, since nobody (that I've seen) is arguing that bitcoin contravenes them directly.
I wonder what percentage of HN readers are like me and just skim through the RSS feed every day. The top of the front page and the worthless submission make it into my Google Reader, and I read what I find interesting. Which is great, but at the same time I don't participate in upvoting articles. I would guess the more passive users would be more interested in the hiring thread rather than extremely trendy topics like bitcoin. But that's the tradeoff. I mostly consume rather than contribute, and therefore just take what I get.
The hiring thread is really only relevant to people looking for work, whereas the Bitcoin stuff, even if (imo) overhyped, is relevant to everyone. So I wouldn't argue it is overrepresented.
Lawyering over the site guidelines here isn't productive, since nobody (that I've seen) is arguing that bitcoin contravenes them directly.