Note: even hard slurs are fine to use metalinguistically or quotatively, as long as they aren't being used to convey the prejudice that makes them problematic. After all, it's hard to talk about words if you can't refer to them directly.
So, if you don't want to, you don't need to censor the word here, OK? (Feel free to make it either way.)
I think the issue is that English pronouns are picky with their modifiers. The rules for that got a bit relaxed for the plural usage of "you", due to pluralisers (like "you all", "you guys", etc.), but not for the other pronouns - not even for the singular usage of "you". This can be shown through the following tests:
- *You idiot actually find her fascinating, don’t you?
- *He idiot actually finds her fascinating, doesn't he?
- *They idiot actually find her fascinating, don't they? [singular "they"]
- You idiots actually find her fascinating, don’t you?
- *They idiots actually find her fascinating, don't they? [plural "they"]
At least for me only #4 is grammatical. The other four are weird.
Your test reader is suggesting a vocative instead. For this, the head is the word found alongside the pronoun; this can be proven because, if there's no noun there, it sounds broken:
5. *You dumb, you actually find her fascinating, don't you?
6. You muppet, you actually find her fascinating, don't you?
7. You dumb muppet, you actually find her fascinating, don't you?
Since the noun is who's in charge of the construction, it gets to pick what's allowed with it - so "you" being picky isn't a concern.
Note comparisons with this/these aren't too useful; they're simply determiners, so they behave a lot more like the/a/an.
I hope this helps.