First of all, no-carrier has a technical 4G (known as 100mb/sec+), and these are all 3.5g. That being said, I THINK google chose the phone based on the hardware from samsung, particularly the processor. I would imagine it is Samsung who actually chose the radio.
(This post is pure speculation of course, and I cant provide a link for factual information)
That being said - I also lament the exclusion of HSDPA+. When companies release a top of the line device, I think it should be top of the line in EVERY area.