In truth I go farther than that. Anyone who has been convicted of any offense, and has served their time, still has the right to keep and bear arms, even though the government will illegitimately infringe upon it.
The government may legitimately revoke rights when someone is convicted of a felony, subject to certain restrictions. If lifetime disarmament was provided for by the legislature as the punishment for a particular crime, such punishment is legitimate. That does not imply that the federal government has any authority to impose lifetime disarmament as a punishment for state crimes, but I see no reason states lack the authority to punish their own crimes with RKBA forfeiture.