It is the school’s responsibility to raise good Catholics, allowing the man to work there so long was a grievous mistake. You reap what you sow, obviously this school failed them for some time to get this backlash. It’s their mess to clean up and if purging is necessary, so be it.
I think that most activist, militant sodomites work under the radar at many of these parochial schools until a breaking point is reached in a decision to go public on their debauchery, such as in this case. I'm not sure that an interview process can be devised that would be decisive enough to detect these sleeper homosexuals and activists. By the time they usually find out, they are ensconced in the system.