I see your first point, but schools place all kinds of restrictions on what students can do during play periods/recess/free periods. I mean, I'm pretty sure if what the kid wanted to sing was "La Vie Boheme" from Rent, he would have gotten a hard no on singing it at all. The compromise isn't, "You can only sing during play period," because a rule that prohibits singing or humming during class activities is pretty much a necessity if all the students are going to have a positive learning experience (I've had hummers in my classes, and it's always distracting to other people, myself included). The compromise is between "you can't sing that song at all" and "you can sing that song as much as you want."

I do definitely agree about the "oppression!" nonsense. I mean, "what is best for the child" is definitely not learning that a classroom won't have any rules or requirements that don't put his personal wants (not needs, but wants) first.