That's a fair argument regarding PSX4Droid, but I doubt that's the case with this group of emulators. Sony doesn't have any relationship with the SNES or the Genesis, so with the exception of maybe a few ported games, it's doubtful they'll be selling that IP on their own store. In fact, the controller on the Xperia Play would make those emulators a pretty compelling reason to buy it.

I'd wager this was related to either ROM distribution or violating the license on the emulator code.