Fuck yes. The man has demonstrated not only the capacity to take and destroy lives for his own personal gain, not only an intense enjoyment in doing so, but demonstrated every single intention to continue doing so.
Sure he could suddenly pull a Xena and become a force for good. But frankly while he's being an unrepentently vile evil dooer, any such deeply unlikely potential capacity for good is in no way outweighed by the proven, actual evil he's done, is in all likelihood will continue to do, and he should be treated on the basis of such.