I don't think they really have any legal standing, but that doesn't mean that they can't coerce Google. I just can't really see why Google would ban yongzh instead of just removing the emulators where they've (allegedly) received complaints from copyright holders. While they may have some interest in making an example of him or sticking to a pretty zero tolerance terms of service on this they're also depriving themselves of a substantial amount of income.

yongzh has received a relicense for gpSP by me, the sole copyright holder of the source he forked off of (he isn't using any code from any of the other forks). So Gameboid isn't violating any license agreements. It getting pulled is either at Google's discretion due to complaints against the owner in general or, more likely, Nintendo pressuring him. Remember, Google makes money off of his sales too. I doubt they'd remove emulators that didn't directly correlate to any particular person's specific complaint (nor would they take a complaint from some random non-copyright holder seriously). Nintendo, on the other hand..