We're dealing with minor children here. They're not being expected to "blindly obey," but rather, to comply with a set of policies that have been established to facilitate their safety and ability to receive an education. "Blind obedience" would imply that when told to jump off a cliff, they'd comply without question. That's not what's expected of them here, and furthermore, you know that perfectly well. Your line of argumentation here is precisely what I'd expect from a 17-year-old, not an adult, experienced with the world, who has the best interests of a child at heart.
Given his very poor impulse control, I'm inclined to think that, unfortunately, this young individual will soon find himself in a different kind of trouble with a different kind of authority.
How exactly does forceably preventing a minor child during his lunch break from speaking with his mother, possibly for the last time ever, when the authorities are FULLY AWARE that a call is from his mother (as they admitted the second call back from her in the office was after they snatched the phone from him and hung up on her) in any way "facilitate their safety and ability to receive an education"?