I agree with both of your thoughts. 1) I can't say for sure because it's just a hypothetical, but I expect that the same people who are championing this prayer as a group activity at a school event would be outraged if anyone other than a Protestant Christian tried the same thing with their faith.

2) As a person who grew up in a religious family, I find the notion of praying for success in a sports game unseemly. "Lord, give us the courage to play to the best of our abilities and the grace to celebrate the result, whether we win or lose"? Sure. "Let's kick their asses and win, we pray in the name of Jesus Christ our Lord, Amen"? Heck no!