Apparently you are allowed to rely on GPS to stop you from going where you don't want to go (the Airspace Aware unit sponsored by NATS)
I rather thought the point was that you are NOT supposed to rely on it. Rather, it's a reminder in case your navigation skills are not perfect. (Whose are?)
...but not to guide you where you do want to go.
Where did you get that idea?
All forms of navigation, including looking out of the window, fail from time to time. Pilots looking forward to a long and happy life do not rely on any one (except on a gin-clear day in familiar territory). Use GPS (most of us do), but keep a visual check on landmarks outside, or cross check with VOR/DME or whatever. Surely, assuming that something might fail is just good airmanship (and certainly part of IMC/IR training).