SS,
I agree with what you're saying & I agree with what others have posted, and, IMO, I feel you are over-thinking it. IMO, you're doubting yourself because you feel he's rude, but you don't want to use the word "rude". Why not? "Rude" describes how you feel & it's not a bad word and based on what you've described, he is being rude. So, what is your fear of the word? I don't see a problem with the word.
SS, you are a gentle, sensitive person. How about taking 30 minutes, write down your thoughts, your speech/presentation and then speak to him.
IMO, if you don't say how you feel ("I feel yr being rude, insensitive/disresepctful when you..."), then you are not being true to yourself, not owning your truth. I know you will not be mean to him, but you will express your feelings in a calm/compassionate way.
However, be prepared that he may move out (which may be a good thing) & you may need to find a new student.
SS, I think this is a really good learning experience for you. You previously mentioned that the young man who was your son's "big Brother" was also "rude" to you, disrespectful in that he failed yo give you advanced notice, right? So, I see a pattern here.
Let me go a bit farther, but with love: We ACONS have been raised to be doormats. Do you feel that you're experiencing a bit of doormatitis with this kid? If yes, then, IMO, telling him how you feel & setting boundaries in a calm, compassionate manner is one of the best growth experiences for you at this time.
xoxo,
ann