Yes, possibly. Should definitely be trustless and we don’t want too much security to rely on an external mechanism, but I’d be interested in exploring this. Most important thing is to keep the bond as small as possible for the sake of UX.
This is a really good way to break the situation down. It seems like the result of the game might almost be miners being the only users to challenge in most cases, although the reward is relatively low. That seems dangerous under bribery attacks.