Not all muzzleloaders are firearms (for those of you who say that they are). This is taken straight out of the Texas Parks and Wildlife Outdoor Annual (hunting rules and regs).

Possession of firearms by felons: A convicted felon, regardless of where the conviction occurred, may not possess or use a firearm (as defined by Penal Code, §46.01) to hunt in this state. Under Penal Code, §46.01, a muzzleloading firearm is lawful if it is an antique or curio firearm manufactured before 1899 or a replica of an antique or curio firearm manufactured before 1899 that does not use rimfire or centerfire ammunition.

So to say a convicted felon cannot use a muzzleloader because it is a firearm is not always the case.