Earlier quoted context omitted.
Someone's not allowed to go to a sporting event because you say so? That's a load of crap. I'll go to whatever event I want. If they have one of these dear leader performances, I just stand there thinking about whatever is on my mind. If you like it, you can sing your little heart out. But I'm not going to not go to something I enjoy because you might get offended at my non-participation in your cult-like ritual
How did we jump from "this is not mandatory" to "you're not allowed"
Also, as "not mandatory", have you ever chosen to remain seated and experienced the reaction from those around you? You'll definitely get the feeling "not mandatory" is a very much incorrect description.