I can give you MY view (as a judge). If you write it, it's public knowledge. Even down to your thoughts, as I view those as a blog or some other similar writing that the wrestler has opted to put up for the world to see.
To me, responding with, "I don't know what you're talking about. I don't do cocaine." When you clearly state that the character is doing cocaine is fine, as long as that denial is part of the overall story (first sign of getting better is admitting there is a problem *GRIN*). But you can't OUT OF KAYFABE state this and complain to the judges. It's written. It's public. You don't want that to be part of your RP battle, keep it out.
If you put it in the Hype area for RPs, that might work better, especially if you let your opponent know that it's off-camera. As a judge, I won't be reading the Hype RPs unless I just want to, as anything there can be on or off camera...and I have enough reading and writing to do w/ this first round!!! Would some schmuck potentially use Hype stuff anyway? I guess, but I wouldn't see why - he should be able to work off your normal stuff or pitch you an angle that he's wanting to use with the Hype stuff. And if you make it clear & they do it anyway, I would just pull a CM Punk and say, "it's none of your business." and ignore such a point he's made. Depending on how you work it, I think it could even work to your benefit.