This is not Ms. Manners. This is Ms. Manners with PMS and a gun.
I have no problem with folks having a good time, but I believe that most logical folks can agree that MOST customers seeking a meal and cup of coffee at 0430 also expect a bit of peace. If one table of rowdy customers is causing problems for all...then it is proper to ask that they calm down...which he did before his personal stroll.
Now that does not give the compaintant the right to threaten....which he didn't.
This begs the question, "Would this loud group have been so loud and obnoxious had a party of policemen been at the next table?"