"He" didn't take the wrong penalty. He took a 2 stroke penalty for breaking the rules. it is up to the rules officials or PGA to disqualify him.
We can have an endless discussion of "what if"....
However haven't there been golfers who lost a tournament because someone called in a penalty, when there is no evidence the golfer was aware an infraction had taken place.
We accept that, we would accept this. Penalty is a penalty.
When playing for fun, my personal rules:
1 Mulligan per round
Double par max per hole
If we all agree "your ball should be right around here" drop with no penalty
Pants off dance off if you don't clear ladies tees. (requires at least 30 seconds of Rodney Dangerfield like dancing with pants around ankles.