It seems that ignorance is a job-requirement for employment in American public schools. There is black-letter law establishing the right of private prayer in public schools, provided it does not disrupt classes, and of students to organize religious clubs.
Presumably once the district superintendent has a brief laying out the relevant precedents, whichever nitwit did this, the assistant principal or someone up the chain of command from him, will get slapped down and an actual lawsuit will be unnecessary.
Teachers are in the lower percentile.