If baseless, non-scientific fears were enough to kill a product, nobody would ever ride in an airplane.
I doubt the radiation will make it through your tin foil hat.
The technologies aren't the only important part; one should consider that a cellphone is talking to an antenna a few miles away, compared to the Glass talking to a device a feet or so away.
Without discussing if Bluetooth and WiFi are bad for your health, it would be way better to keep those transmitters and receivers close to your head than for instance your upper body.
Your skull is quite dense and blocks radiation way more than the soft material that protects your heart and lungs.
Rather irrelevant in the GHz range, where density is much less significant than the chemical bonds and conductivity of the material. In fact the soft tissue would likely be a better absorber due to a higher concentration of water.
Isn't the fact that water absorbs waves and heats the main hypothetical danger for the brain?
Not to mention the organs it's nearest to in your pocket