We're talking here about the emulator including Sony copyright.

For god's sake, you even quoted the relevant part! The implication of the accusation in that line of discussion was that the emulator contained actual warez-illegal stuff from Sony, and that we can't say it's not warez if we don't have the source. Thing is, you can. You could cross-compare Redump's PS1 library and BIOS'es and any known SDK leaks with the apk contents (or the memory at runtime) with a hex compare tool to find if it has those stolen assets hidden inside.

Deliberately going from "closed source" to "it distributes pirated ripped Sony stuff" is a hilarious way to advocate open-source as far as such heavy-handed tactics go, I'll give you that.

About your other point, "it uses illegally obtained documentation and the author's mind was tainted with forbidden knowledge and his sins were transmitted to the program, I have a hunch that's the case, so it must be true" sadly (?) doesn't count as either a convincing legal argument to convict the author, to get Google to delist his app, or to force him to release the entire source code unconditionally for the open-source fans to wave it in celebration as a trophy and put it in Github under the GPL license or something. That's pure fantasy.

You'll need something to prove your claims that the emulator is illegal (which is no small claim). But you're not even putting much effort in launching stuff at the wall for something to stick.