So is it ok for audience members to sing along during shows?

I was wondering what people on the board think of this and I couldn't find another thread about it.
Recently I read this article: www.theroot.com/ain-t-too-proud-to-sing-claiming-black-space-on-the-gr-1834448909

Summary:

"I visited a show. My mother is doing what black folks do at a musical, she sang along."

"And then from two rows in front of me, a balding white man turns towards my mother and says, “SHUSH!”

"This man shushed my mama?"

"When intermission hit, I walked up to that man."Was that you who shushed earlier?” I asked.

"Yes," he said, open and pleasant, as if he thought I was going to thank him for lending a hand to the larger, "well-trained" theater-going community.

"Please don’t shush my mother again. I just wanted to let you know that it was not kind what you did and if you shush her again, I’m going to sing along with her." 

"Well," he said, “I didn’t pay money to hear your mother sing."

"Oh, Black Jesus, help me. Was that a snub about my mama?"

"And so I said, “Let me tell you something—When you entered this theater, you entered into black culture. People will sing along. It’s what we do. And if you wanted a quiet theater, you should’ve seen My Fair Lady.”

"When I went back to my seat, my mother asked, “What did you say to him?” And I told her. And she laughed and laughed."

She also talks about how she visited Hamilton once and made noise during the show and another horrible white man looked at her in an annoying way.

Now, this is an American article and I have noticed that in current American society people can't look past race and make everything about race. I think we need to see this article in perspective. On American fora people are saying: That white gatekeeper needs to stfu, and those kind of comments are generally embraced and accepted there, as well as these kind of articles. In fact, if you suggest to look at people and the actual subject, your posts tend to get removed there. There is no life beyond race, they must think. But to me, this is all about human respect. 

To me, the gentleman was fighting for decency and respect but it was a lost cause unfortunately. Because the gentleman was right, he did not pay this amount of money to hear her mother sing. The fact that he had to explain himself is bad enough. How extremely rude to try and silence this gentleman by saying "when he walked into the theatre he entered black culture". He did not. He visited a show he was interested in and he wanted to concentrate on the actual show. I am wondering how other audience members reacted on this? The disdain for other people and races of this lady is unbelievable.

I also don't get the "insulting white people's balding heads" for no reason. I believe the man would have shushed anyone making noise during the show. My opinion is, just because you can engage with the material on a different level, doesn’t mean you can act however you like in the theater.

If I was in the audience and people were disturbing the show in any way I would shush them too. I would also accept an apology from the lady at intermission. But if I was assaulted like that at intermission, I would have had the lady removed from the theatre for the 2nd act.

What are your opinions on this and have you had experiences like this?

Edit: I think that all theatregoers should be some sort of "gatekeeper" in a way. People pay $170,- for a ticket and sometimes have to save money all year to be able to purchase one. It's just common sense and general respect.