A ton of coaches are, and frankly, they should be able to. Meanwhile, I only see two points where these yahoos might have a legitimate complaint:
1. Religious studies between drills (honestly, there's almost no way that's an accurate description...any coach would be insane to interrupt practice like that)
2. If Trapp really wasn't selected by the students
You can't ask people not to be involved in or lead private religious meetings, no matter their position or manner of payment (hourly or salaried). To get any serious traction with this, they'll have to produce examples where players suffered by not attending, and since they didn't mention any, I doubt they have any.