There's still a problem with the government school inviting anybody in to proselytize ~ they simply are not Constitutionally eligible to do that. You're not self-aware at all, are you? This is exactly what this young lady did, and exactly what rational people are objecting to.
SD
So, she proselytized ~ none of your damned business. She was invited to speak. Unless the school district was in the business of DICTATING THE PRAYER, something which is Constitutionally prohibited (according to the Supreme Court), she could pray as she wished.
Your narrow, petty, sectarian viewpoint on what is permissible religious expression (or prayer) in public is the problem ~