So this is just another open-vs.-concealed debate, because some of us just aren't mature enough to stop ourselves (or hit the "report post" button).
To sum up:
1) He may have been deliberately carrying openly in a rather awkward fashion, with his "cover" shirt bunched up over the gun. Not my first guess, but could be.
2) He may have been carrying concealed and his shirt GOT bunched up over this gun, exposing it. That kind of sounds like how I'd have read the situation, but I wasn't there.
3) There are some pretty gentle and slick ways of bringing up the subject as a non-threatening, low-key conversation. Some of y'all are pretty smart about that sort of thing and know that -- whether he was trying to OC or trying to CC -- you can turn a little word of aid into a happy few moments of chit-chat with a fellow gun guy. Maybe make a friend! Lord knows some of y'all sound like ya need one.
4) Hey, talking to strangers is SCAAARY! He might be ALL OFFENDED because he's an open carry DIE HARD and you just deeply offended him by suggesting that his shirt was bunched up over his gun! Why, maybe it's much safer just to keep
weeery, weeery quiet and just avoid contact with another human.
What was it John Wayne said? "
I won't be spoken to. I won't be greeted. I won't be engaged in conversation. I don't do these things to other people, and I require the same from them.” Something like that...
And...
5) I'll carry open sometimes. I carry concealed a lot of the time. It doesn't matter which, or either, here so there's no harm either way.
BUT, I DANGED SURE would want someone to tell me if I was walking around like a sloppy moron with my shirt tail bunched up in my belt, my collar, my holster, or whatever else. That just looks slovenly and unkempt. I'd be mighty thankful if someone would help keep me from looking so unpresentable -- whether my gun is covered or not!