I did not see a response from the devs to the above. It does seem within the realm of possibility that timestamp mismatches and reliance on an external data source could be exploited by sophisticated actors to tilt the odds in their favor, particularly by harnessing mining power. Is Chancecoin provably fair...for the house?
But to exploit this if I understand correctly, you must attack the whole Bitcoin network which is not worth it at all.
So it is just impossible.
I don't see why any of the major bitcoin mining pools couldn't do it.