I'm going to disagree with Patrick and animuson and state that I do consider this a bug in the association system.
On Stack Overflow, we've encountered many cases where sock puppets and their operators voted up their accounts above the association threshold and created accounts on other sites to establish the association bonus. We then deleted their Stack Overflow puppet accounts once we noticed them, but they were able to repeatedly recreate the Stack Overflow accounts we deleted, get the 100 point bonus again, and resume their voting puppetry from them.
In addition to the example posed in the question, this just happened today. Yes, it's an infrequent thing, but it has happened more than once on Stack Overflow and can be extremely annoying to deal with when it does.
Once an account that has received the association bonus has been deleted, it should not be able to receive that bonus again if it is recreated.