The guy was charged with voyeurism. From my quick googling, it seems like the laws say to be charged you have to be spying on someone or recording/photographing them, so I still don't see how this is against the law, but it's obviously gross.

Edit, I guess this is probably the part that he's charged with so maybe makes sense.

"The elements of voyeurism under R.C. 2907.08 require proof beyond all reasonable doubt that the defendant:

(A) for the purpose of sexually arousing or gratifying the defendant committed trespass or surreptitiously invaded the privacy of another to spy or eavesdrop upon another person;"