It depends upon whether your son applies to an audition program AND as a regular liberal arts students, and, of course, if the school permits applying. It’s ways. My son was rejected by SUNY Purchase when he applied to their audition required theater program. I don’t remember if he simply did not apply as a regular student as well. He was accepted to CMU in their school of H&SS but waitlisted for the School of Performing arts. Same with Emerson. He did not want to go to any school where he was not accepted for theater. He was accepted at a number of schools with excellent theater programs and facilities but did not require an audition and those were serious considerations.
I agree that an upward gpa trend will be looked upon favorably, as compared to someone with similar gpa but not with the upward trend. However, we are talking SAFETY, which to me is a sure thing. I’d place such schools as targets. A good safety school would be one where he is certainly going to be accepted, is definitely affordable with no contingencies, and has a theater program. You only need to nail one of those and then deal with the targets and lottery tickets.
My son had a number of Musical Theater (his ideal program) schools with required auditions , theatre schools with auditions with good music facilities, schools with good performing arts programs with no audition component in his mix of schools. He ended up with a mix bag of acceptances in all of these categories. He did have one early acceptance that was his safety, so he could take on as many long shots as he could schedule. I think it took some stress off the year having a place secured early.