Oh please, it is theatre school not divinity school.
Let 'em rip.
If they haven't said much less heard vulgarity and/or profanity they have no business being in the theatre, period. Exception is if you are auditioning for a church related or religious production.
Profanity is 'taking the diety in vain'. Vulgarity is everything else.
Things like 'holy crap' are a hybrid.
"If my life weren't funny, it would just be true. And that would be unacceptable."
--Carrie Fisher