I’d say they pretty much look normal.
If the black families on my block decided to have a get together thats about how they would look - except the crowd would be bigger.
And yeah, the black guys, even the old dudes, would look a little tough - since most are retired 82nd Airborne.
The feral gang bangers hang out down on the Murk and look a lot different.
Again, I agree that they don’t look like feral gang bangers, but they don’t look like a bunch of nuns and librarians either. I could see that group getting loud and rowdy, especially after a long wait. I could also see them not being rowdy.
Also, the hard working, law abiding, black people on my block would probably be dressed a little more respectably and look less rough around the edges than some of the members of this group. They would also probably call ahead if they had a group of 25.
Restaurants are typically not in the businesses of turning away paying customers, for no reason, so I think it is more likely some members of the party were misbehaving, but at this point we don’t know and we may never know.
As I said, large groups of people, regardless or skin color or clothing, can often get loud and obnoxious. This is especially true where alcohol is involved, and the restaurant apparently has a bar. Most groups waiting a long time to be seated would have some drinks at the bar.