You can call it whatever you want in theory, but unless you actually have heard and experienced it in practice, I would hold the thought and not make big statement with words like “disastrous”.
I consider myself music literate (I sing and was in a band for years back in the high school and college days, can tell when things sound out of tune), and I was totally surprised when I didn’t find the Speech Rescue feature interfering with my music enjoyment. But everyone is different and you may not find the result acceptable for you while I do.
I only talked about Speech Rescue here because you asked me specifically, so I really have no reason or skin in the game in terms of trying to promote it for music listening. There’s no reason why anyone has to be stuck listening to music with Speech Rescue on when there’s an option to turn it off and when built in Music program doesn’t have it enabled in the first place. But I thought it to be peculiar that I don’t notice it to be “disastrous” like you tend to think it should be, so I thought I’d mention it, that’s all. Whether anyone believe it or not is up to them. I’m just relaying my personal opinion on it.
But I think if I’m watching a movie and I want to have Speech Rescue on so I can understand the dialog, I don’t really worry too much about Speech Rescue ruining my experience with the music in that movie at all. Not once had I ever thought that something was very off with the music in any movies I’ve watched so far while Speech Rescue was enabled for me.
In the Speech Rescue white paper that I read (I know, I know, many folks on this forum seem to strongly dislike white papers, I don’t know why, maybe because they don’t understand them so they distrust them?), it says that "Speech Rescue utilizes principles of auditory processing (cochlear filtering) so that frequency lowered sound is minimally compressed on a psychological (critical band) scale. Maybe this has something to do with helping making it not sound “disastrous” to me. They go into details about this cochlear filtering in the white paper if you’re curious enough to want to read up on it.