I seriously don't see that there is a gray area here at all. Yes, Rockstar may have been lazy for leaving the code in, but they never intended that portion of the game to be played. If they intended it, it would have been in the game, period.
The fact is that a LOT of games have levels, textures, etc., included with the game that are never accessible in the final product. LoZ:WW had test levels that could actually be played with AR-type devices. Games are rated on the content that is presented to the game player, not the content that could be accessed by modders or cheat devices.
In reading about the Hot Coffee mod, I also read that modders found skateboard code, textures and code for brothels, etc. It's stuff that Rockstar toyed with and ultimately decided that they couldn't, or didn't, want to include in the game. Maybe it would have been easy for them to remove that code and/or textures, but then again, maybe it's not.
Anyone who has done any coding would realize that a lot of stuff is recycled throughout an application. Who's to say that the code used for Hot Coffee wasn't also shared with the Low Rider contests (using the analog stick for motion seems very similar)?
The only thing that pisses me off about the whole situation is that Rockstar is not fessing up to the fact that it is their code. Why not just say it was something that they toyed with and ultimately decided not to use? With all of the other controversial content in that game, they are afraid of admitting that they put in a "sex" mini-game that was never used?