Definitely stop ignoring him.
When I tt someone out I often forget to keep talking to everyone, I then get told someone is thinking of moving but they refuse to ding me at all even for stupid things - so I speak to them and they moan that they haven't seen me in ages then I save and quit, go back on and they ding straight away!
If he's your 10th he can still move, it could take ages though. There was a thread not so long ago that asked about the 10th villager and a few people have had theirs move out, but the majority of people didn't have any luck.