Hmmm, yeah, that is a potential reason I suppose. What better way to find out exactly how to disrupt your disruptor (likely via regulation) than working hand in hand with them? I'm not quite sure I buy it, but it certainly wouldn't be outside of the realm of possibility for banks.
As a former employee of one of those banks, I can tell you that you are overestimating them. They are not even thinking about keeping their enemies' close or disrupting the disruptor. Who gets paid a bonus for that??! Nobody.
