Sure, but the reason it caused a rating change was because the "nudity" wasn't modded in. It was on the disc, in the basic download, whatever - it came packaged with the game itself. No nudie mod for Skyrim (I dunno, do they exist? *cough*cough*) has changed its rating.Content that MOST people accessed through the hot coffee mod.
The Hot Coffee debacle wasn't mod-related. Sure, most people used the "mod" to access it, but since that was something you could literally do yourself on a console with just some commands...