Some of my indignation is driven by the fact that I was watching the kid. He was showing signs of fatigue (taking more time between pitches, shaking his arm out, rotating his arm, favoring the arm when walking to and from the mound). He also had left the game on Saturday with arm complaints.
When you add in the number of pitches he threw warming up for each game & in between innings, he must have thrown over 350 pitches over the four days. I find that a troubling number
By the way the kid is a junior. Yes, he wanted the ball but that is when adults are supposed to step in and make decisions in their best interest.
The reason I find the rule egregious is it well known that all innings aren't created equal. You can have a 3 pitch inning and I have seen 35+ pitch innings. By the current rules, this kid could have thrown five more innings the next day. I don't think the rule goes far enough to protect the player from themselves and over zealous coaches.