My Boxster does the same thing, which is indeed annoying, but at least it doesn't disable any functions while driving. That would be infuriating.
One thing that helps in my case is to double-click the MAP button instead of pressing it only once. The first keypress has the effect of accepting the nag screen, while the second pulls up the map. Sounds like you get the message even when you aren't using the nav system, though, so that probably won't help.
If I were any more annoyed about the nag screen than I already am, I'd bodge in a small microcontroller to double-click the MAP button whenever the car is started. (I already had to add one to force it to remember Sport mode across drive cycles.) That would have the significant advantage of working without digging into the touchscreen logic. So if the Ghibli has a physical button somewhere that has the same effect as clicking "OK," that's probably your best option.