Nothing really stops you from changing the firmware on Google Glass to a custom one, with all of Google's spyware ripped out.
Not to bring anybody down... but seriously... we intentionally left the device unlocked so you guys could hack it and do crazy fun shit with it. --- Stephen Lau, Google X Lab
There's source code available for the kernel as required by the GPL as well as for other essential components, so custom firmware is definitely possible for it. Someone out there will probably eventually wind up selling medical editions of Google Glass with custom firmware with HIPAA compliance baked in and apps to interface with common medical information systems, although such a thing will likely be far more expensive than the consumer edition. Someone further down commented that it would cost $19,000, and well, I imagine they're not far off the mark, and perhaps even underestimating it. Certification is an expensive business.
I frankly don't get why there is so much hate on Google Glass. Indeed, the use that is being pushed for it as a consumer device is very creepy from a privacy standpoint, but you don't have to use it as Google intended. As William Gibson famously said, the street finds its own uses for things, and Google hasn't done anything to hinder that, in fact they are actively encouraging it.