This statement was actually referring to decisions that restricted prayer in any sense - which is a violation of the Free Exercise Clause. I do not believe The Constitution allows for the courts to restrict any form of religious expression by individuals, whether they be teachers, football coaches, or student valedictorians. You can disagree but you can't parse the Establishment clause or show me from the founder's writings where schools are considered off limits for any prayer situation. In fact, the founders encouraged the reading and teaching from the bible in schools.
Nor do I. And neither do the Courts. But the cases you are complaining about is the restriction on teachers, football coaches, etc. leading others in religious expression, whether they want it or not. And when those people are acting as agents of the state, using state property and a state microphone.