Depends on the rules of the no deposit bonus, if he knows how to avoid cheater (multi accounts) then it will be fine to offer no deposit bonus.
Limiting the no deposit bonus for bitcointalk members only with more requirements (rank, merit, etc) can be one of the ways to avoid cheaters.
Promotion should be calculated and prepared wisely in order to lose a lot of money.
Yes, i think we are going to give exclusive bonus to Bitcointalk members (no new accounts or spam accounts)
If you are going to make the no deposit promotion exclusive for bitcointalk members then you will not get enough traffic o your website and you will end up with few customers who may or may not continu to play on your casino. Better make similar promotion on different gambling related platforms/forums to attract more customers.
Other types of promotions on bitcointalk isn't a bad idea though. Take a look at the games and rounds sub board to have an idea on what kind of promotions you can run.