but from what I know almost all (or maybe all) Bitcoin paying campaign aren't paying for posts in off-topic.
Two bitcoin signature campaigns are paying their participants for making posts on "off-topic" board.
If majority of bounties are paying for posts in it, then disabling signatures sounds not bad.
Almost all of them don't count posts made on "off-topic" board.
This. OP could contact those 2 campaign managers to express his concerns.