Personally, if this was a "friend" of mine, I would say something to him. If it was an acquaintance, I would not. It would definitely depend on our relationship. I think it is important for true friends to keep each other accountable in life.
This doesn't sound like a bad job of coaching but rather a poor example of general behavior. In other words, if I had an off night officiating...made some bad calls...missed some...(more than usual I mean
)no, I wouldn't necessarily want my friend rehashing it with me at the neighborhood barbecue. If this friend / coach played zone when he should have played man, I'm probably not talking to him about it.
However, if I was yelling at people in the stands, giving the crowd the finger (which I saw an official do several years ago - behind his back, not straight up in the air for all to see), etc. then I would want my friend to take me to task. I think we (in general and me specifically) could use more of that.
On a side note, depending on how close to the end of the game the questioning every call started, this would have likely earned a T, friend or not. That saying something about EVERY call is probably my biggest pet peeve, for the time being.