Good to see the ancient traditions being maintained
In Greece and Rome the phallus was a symbol of good fortune and abundance. It was regularly carried on religious processions - sometimes requiring several people to do the job.
There was even a deity called Fascinus who was represented by a set of male genitalia, whose image was kept - for some reason - by the Vestal virgins.
So if the students are told to take their symbol down, they have several reasons for refusing on religious grounds. Depending where you work, this image might not be safe for it.