I believe Wirt dies after you click him, just as the guy in a bloody pool in front of the cathedral dies after you talk to him in Diablo 1. It doesn't matter whether he goes to heaven or hell, they are getting less and less distinct as the battle goes onward.
Warriv is great for trickery in act 1, I use him to xfer items in "perm" and "mule parking" games. It looks suspcious when someone runs to a waypoint, but when you just disappear, no one seems to notice.
Ohm runing a wirts' would not do much damage the 10 or so average damage would only increase to 15 average damage. A level 69+ would be pressed to find anything that he could kill using a weapon that does 15 damage, on average.