Good for him. Shows you can't judge a book by its cover.
Actually, I would rather that a felony conviction, in and of itself, not involve a loss of gun rights. About 80% of felony convictions are for non-violent offenses, and I see no reason why someone convicted of fraud or marijuana possession should lose that basic human right.
https://www.bjs.gov/content/pub/pdf/fssc06st.pdf
Historically a felony meant a truly serious crime, one which was probably enough to consider the death penalty. At that time it made sense to restrict a felon's gun ownership by default, but it doesn't today. In Tennessee v Garner the Supreme Court gave this rationale as to why shooting a fleeing felon was not legal unless the felon posed a threat. For the same reason, the right to self-defense should not evaporate with a felony conviction.