Ohio started to allow rifle this year for deer hunting, though in straight wall variations only, which typically aren't calibers that one would suppress (though you could). It's mostly geared to varmint hunting where one would use a bolt-gun or AR, and, be shooting quite a bit during that time. It's saves on your hearing, which is always a good thing. How many people do you see carry ear plugs with them into the woods? damn few.
Also of note, shotgun suppressors have typically been somewhat of a pipe-dream, however, SilencerCo recently came out with a suppressor for them within the past year or so that is actually pretty effective.
In the end, there's no real reason why they SHOULDN'T be legal. I mean, what exactly are they hurting? It goes back to the concept that criminals (poachers) are going to be criminals regardless of the law.