TL;DR : yup, looks like it, but it’s going to require a standalone, carefully designed box (or boxes).
@brian (RoonLabs’ CTO) chimed in on this here. @Jeffrey_Moore, who makes a similar use of Roon to what you’re describing, had an exchange with him further down in that thread.
Users without deletion privileges has been a request for some time (“let my guests pick music, not delete albums” typastuff). Custom tagging already exists, sorta - you could add a “don’t air” artist, for example, and then sort by everything BUT “don’t air”. You could also make the tracks you don’t want aired invisible in roon (“hide track”), but given that “unhide tracks” is directly underneath that, you might want something that’s a bit more resilient to user error assuming “multi user” won’t be in the next update (and I’m sure people smarter than myself would have better ideas than those two).