Nobody said anything about allowing a felon to fire guns at a range or anywhere else. Nobody said anything about a felon handling guns. Neither did the op. Nobody but you.
I don't know about you, but when I go to the range, I don't go up and down the line asking everybody for a copy of their criminal record.
So your not comfortable having a felon next to you at a range, but once he goes through the proper channels and expunged his felony you feel comfortable?
At what point in time do you consider a felon to have paid his debt to society?
If it legal for a person convicted of a DWI, with a suspended drivers license to be a passenger in a car, why is not ok from a legal standpoint for a felon to be a range **watching** his son shooting guns.
My advice to the op, have a "no touch under any circumstances" talk with the dad, go and enjoy your day.
My opinion and my opinion only, if it were me, at this point, I would shut up about it and move on with my life. I can't see how futher dwelling on it can be benefitial.
I would make sure all my T's were crossed and my I's dotted, though, just in case.