I'll post the full statement, because it's the first time we've heard any concrete clarification from Rockstar on the subject.
“We have always appreciated the creative efforts of the PC modding community and we still fondly remember the awesome zombie invasion mod and original GTA map mod for GTAIV PC among many other classics. To be clear, the modding policy in our license has not changed and is the same as for GTAIV. Recent updates to GTAV PC had an unintended effect of making unplayable certain single player modifications.”
“This was not intentional, no one has been banned for using single player modifications, and you should not worry about being banned or being relegated to the cheater pool just for using single player PC mods. Our primary focus is on protecting GTA Online against modifications that could give players an unfair advantage, disrupt gameplay, or cause griefing. It also bears mentioning that because game mods are by definition unauthorized, they may be broken by technical updates, cause instability, or affect your game in other unforeseen ways.”
So according to Rockstarhanded out to those using cosmetic mods were accidental, which is not entirely surprising. Mods and cheats are often very hard to tell apart, as both alter a game's memory usage in similar ways.
Meanwhile, Rockstar continues the hard job of tracking down and punishing GTA Online cheaters. Although the developer admits it's “unrealistic” to say that they can solve the problem, they will continue to regularly roll out fixes for exploits and work aggressively to stop griefers.