Completely agree! I ran into this a couple of weeks ago in this thread. I had manually added some necessary cautionary accidentals in a part, but didn’t need them in the other parts where this line was cued. My mistake was simply unclicking the toggle in the cue rather than cycling through the visibility options, so I lost the accidentals in the source as well. It still seems very counterintuitive to me that unclicking a toggle in a Cue should have any effect at all in the source, but it does.
I can’t think of a reason why I would ever want edits to a cue to affect the source material, so I definitely am in support of the layer of disconnect principle here.