Can a Barbarian do non-leathal Damage while Raging?
Can a Barbarian use the Enforcer Feat while in a Rage?
http://www.d20pfsrd.com/feats/combat-feats/enforcer-combat
Can a Barbarian do non-leathal Damage while Raging?
Can a Barbarian use the Enforcer Feat while in a Rage?
http://www.d20pfsrd.com/feats/combat-feats/enforcer-combat
While in rage, a barbarian cannot use any Charisma-, Dexterity-, or Intelligence-based skills (except Acrobatics, Fly, Intimidate, and Ride) or any ability that requires patience or concentration.
Nonlethal Damage with a Weapon that Deals Lethal Damage: You can use a melee weapon that deals lethal damage to deal nonlethal damage instead, but you take a –4 penalty on your attack roll.
I don't think dealing non-lethal damage take any more patience or concentration than fighting, flying, riding a horse, etc.
If he doesn't want the penalty, he could use a sap or whip.
Intimidate is specifically mentioned in the list, so I think Enforcer is fine.