I don't think they're bots. I recognize about half the names, and though they may not be regular HN contributors, they're real people (some of 'em, at least).
It's distasteful.
I'm sure that a lot of the folks on HN are here because someone in a startup emailed the other folks they know in startups and said "check out my thread on HN and give me a vote". That's how I first found out about it and YC.
Spam might be distasteful, but I don't think there is anything distasteful about someone from a startup introducing other startup founders to the site and asking them to get involved. It might take new members of the community a while to learn the rules, but there is no innate correlation between being new and being a spammer. And HN isn't normally an elitist place where length of tenure implies respectability. I don't think anyone wants to see it turn into the tech community equivalent of a country club.
Interesting.
Edit: I suppose the occam's razor explanation is that someone emailed (or twitted) the link around asking for people to show them some support in here, instead of an intricate botting conspiracy.