Your assumption as to the reason for the bump isn't quite correct. It's not bumping questions that have no selected answer, it's a bump of questions that don't have any upvoted answers. That was the case here. It has several answers against it but none of them have been upvoted. (It's what Stack Exchange refer to as an unanswered question - because unless someone found one answer useful then it can't really qualify as answered)
Also, don't get the 'accepted' answer option that the question asker can do against one particular answer mixed up with what qualifies as the 'best' one. Just because the person who asked the question isn't going to be able to mark one post as 'accepted' that doesn't mean there isn't value in serving up that question to everyone. People can still upvote useful answers so we can see the best answer that way. The voting score of answers is arguably a better indication of best answers.
Personally speaking, once a question has been written and posted I tend to think of it as then belonging to the whole community, not the person who asked it. Sure, that person is the one who'll get the immediate benefit from it, but we're not here to help individuals; we're here to provide a repository of useful information for anyone who has a particular problem. If bumping a 0 answers question up to the top of the page helps get that question some useful answers then that's to the benefit of everyone really.