I'm not convinced that they would care if there is collusion. They obviously don't care about robots playing at the lower FL stakes even if they aren't officially allowed. That's perhaps more of an iPoker network problem than a WH problem to be fair. Both robots and collusion in any form is cheating of course.
You post evidence that is good enough for me. The evidence of existing robots is even better because of millions of played hands. (I don't want to recap about bots here.)
But, if so happens, the rake keeps coming for the house. Thus, it's a no win situation for WH, or any other smallish site for that matter, to either acknowledge or dismiss claims about ongoing cheating. It doesn't attract new depositors and traffic might drop instantly.
Still, maybe the promotion collusion is easier for WH to deal with than robots because they may be able to simply freeze (permanently of course, without actually investigating anyting) the listed players accounts and even look good in the process - without losing considerable table action.
I wouldn't think that the colluders are bots because it wouldn't be worth the programming effort for a fistfull of dollars. Thus they aren't as good rake generators as the bots so WH might just swat these guys.
Keep us informed.
/Johan =