Sam, if they are too long for him, then there is an easy solution that doesn't make everyone on this site want to climb the walls.
Tell him to smoke for his 20 or 30 minutes, then let the cigar go out naturally in the ashtray.
THEN, use his clippers to cut the cigar, about one inch behind the burn line. Tell him to put the remaining cigar into a separate plastic baggie and back into his humidor.
Next time he smokes, he can pull out the baggie and smoke that one, and then just toss it when he's done.
What he's doing is the equivalent of cutting a can of beer in half, then plastic wrapping both open ends, and then telling shocked onlookers it's because he can't finish a whole can in one sitting.