> Are public employees not allowed to pray on the job?
The school district practically begged the coach to work with them to find an avenue for him to express his religious beliefs through prayer, without creating a coercive environment for students. At every opportunity, the coach declined to find a way forward that didn't violate the establishment clause.
It's important to know that "prayer in schools" is a rallying point for conservative christians, and the coach's behavior was intentionally provocative. Holding big, public prayers like this is a strategy designed to continually test the limits of the establishment clause, with the goal of ultimately breaking it.
A piece of anecdotal evidence that I always think about when stuff like this comes up - I went to a very, very conservative christian school. Prayer was pervasive (as you might expect), but it was never used to make a public scene like this. Ever.
Finally, his behavior is an affront to prayer itself, which Jesus himself makes clear in Matthew 6:5-6.
> And when you pray, do not be like the hypocrites, for they love to pray standing in the synagogues and on the street corners to be seen by others. Truly I tell you, they have received their reward in full. But when you pray, go into your room, close the door and pray to your Father, who is unseen. Then your Father, who sees what is done in secret, will reward you.
It says a lot about his motives. That's not exactly an obscure passage of the Bible.