Humans can get the Lawbreaker stunt.
Human-fallen hybrids can't, not anymore than fairies can. There's something in the driver seat that isn't human.
As for the Wardens, they might never trust a former Denarian, but they wouldn't hunt him for what he did while he had his coin - the Accords forbid. Now if the Denarians didn't sign the accords that would be another matter, but one faction can't punish another faction's member.
Now if he has some powers remaining, he's now under the White Council as far as the Accords go. If the Wardens know about his past they would probably watch him like... Well, like Morgan watched Dresden - waiting for him to screw up so they can take his head.
Richard