Can I deer hunt with a muzzle loader in Ohio with a felony ?

They are still a fire arm as defined in the Gun Control Act of 1968. As such they fall under the Federal law of such
Ohio Gun Laws - What are the Gun Laws in Ohio

Ever consider bow hunting

Actually, I don't believe they are.

"... 3) The term "firearm" means (A) any weapon (including a starter gun) which will or is designed to or may readily be converted to expel a projectile by the action of an explosive; (B) the frame or receiver of any such weapon; (C) any firearm muffler or firearm silencer; or (D) any destructive device. Such term does not include an antique firearm.
...
Antique firearm. (a) Any firearm (including any firearm with a matchlock, flintlock, percussion cap, or similar type of ignition system) manufactured in or before 1898; and (b) any replica of any firearm described in paragraph (a) of this definition if such replica (1) is not designed or redesigned for using rimfire or conventional centerfire fixed ammunition, or (2) uses rimfire or conventional centerfire fixed ammunition which is no longer manufactured in the United States and which is not readily available in the ordinary channels of commercial trade.. . "
The Gun Control Act of 1968, Public Law 90-618

But it is still a "firearm"

Yes and no.

Yes according to the dictionary.

No according to the statute.

Go figure.

Don't think I would risk 10 years in prison on argument of the term in court.

I have a close family member doing 10 years for a old shot gun, that was rusted shut, it was a wall hanging. You could have never ever made it shoot. Well after two drug raids finding nothing ( OK he was a big time drug dealer they could just not catch him) they saw his display on the wall.
And he is serving 10 years for it right now in Federal Prison.

In court of course they had the gun all cleaned up and looking shinny. ( they had to get it to test it or so they said.

But it was manufactured before 1898 and designed to use center-fire ammunition.

I will admit, however, that there are some modern muzzle-loaders which were not designed or manufactured prior to '98 and therefore would be considered "firearms".