I agree with you that BB might be making many moves here, since its HU, I kinda ignored that in my post.
But given its heads up, it is also less likely that BB will only call a raise with a lesser flush.

If he is making a pure bluff without a [img]/images/graemlins/club.gif[/img], isn't he likely to fold to a raise, but bet the river if called?
Or is your point mainly that he is most likely to be betting a lone [img]/images/graemlins/club.gif[/img], making it necessary for us to charge him the maximum for his draw?