Casino wouldn’t serve alcohol to my friend on his 21st birthday because “he has to wait 24 hours”

Last night I took my friend to the casino for his 21st birthday, we got there at about 12:10am, we got his casino card all set up perfectly and headed to the bar to get his first drink, the bartender told him that he can’t serve him alcohol because even tho it’s his 21st birthday, there’s a law that he must wait 24 hours before he gets alcohol. I had a feeling this was BS cuz my 21st birthday was 4 days ago and I was able to get alcohol at 12:30am, the time I came in and it was at the same casino. He brought security over and they verified he couldn’t serve him alcohol. We would have left but we already took shooters in the parking lot when we got there and I didn’t want to drive. We decided to gamble anyways and at 1:39am, 9 minutes after they stop serving alcohol, they came up to him and apologized that they made a mistake and they could have served him alcohol which obviously at that point it was too late and they wouldn’t comp him anything either so kind of a ruined birthday for him.

Edit: before people start saying that there was some alternative motive like not wanting to deal with a drunk 21 year old, there was none. The simplicity of it is that the bartender and security was fed misinformation by another security guard and they both messed up by not directly asking a manager.

TL;DR: Casino thought you had to wait 24 hours to serve alcohol to a freshly turned 21 year old adult, didn’t catch the mistake until 9 minutes after they stop serving alcohol and wouldn’t comp him anything.