This is inaccurate. We’re talking about a PhD in Music Theory, not a DMA in piano, or even a PhD in Composition. A graduate degree in Music Theory requires the ability to research music, not play an instrument or compose a piece of music. So providing the best possible piano performance that they ever have heard will still not demonstrate that a person has the ability to produce a substantial piece of academic research.
For example, the requirements for admission to Northwestern’s Bienen School of Music’s PhD program include (on top of CV, GRE scores, LoRs, transcripts, etc):
They do not require a piece of music.
If @sackblake has some serious achievements in music down the road, that would put them in a more competitive place, though they would still need to demonstrate ability to do research in music theory. Transferring to a four year college with a good reputation in music theory, so that their undergraduate degree is from that college, would also help.
@sackblake could also attend a less “prestigious” PhD program, but that would cut the slim chances of a faculty position in the future even further.
PS. “prestigious” means “prestigious in the music world”. So Indiana University, while an excellent school, is not typically thought of as a “top 20” or even “top 50” university. However, their Jacob’s School of Music is one of the very best music schools in the country and the world.