Googlers say Glass wasn't rooted because it was "intentionally left" open
The first out of the gate was Google engineer Dan Morrill, who was quite vehement in his argument saying, "This is not rooting. Nothing is rooted. There is no root here! This is 'fastboot oem unlock'. It's not rooting if they let you do it on purpose!" And, Stephen Lau, a member of the Google Glass team, added to that saying:
That all makes perfect sense, but Saurik still stands by his claim. He has come out to say that he didn't use fastboot oem unlock, because he cracked Glass before Google had released the source code. He says that what he did is "rooting" because he used a known exploit in Android 4.0, which took him just 2 hours to learn and fix.
So, it sounds like Saurik did legitimately hack Glass, but it also sounds like there was absolutely no reason for him to do so, because he could have simply used fastboot oem unlock after Google released the source code. Saurik didn't go into what - if anything - he was able to do after cracking Glass, or if he is now working with the official kernel code.