I don't think the carriers are releasing it. Maybe that HTC employee shifted the blame to the carriers. I think it won't work like this because the unlocked devices and international versions are that, international, carrier independent phones. I bought the US unlocked model and I live in Mexico. The phone is not available on this country yet.
If what that rep is saying is true, people wouldn't be able to update as long as their current carrier sells the phone and has tested the updates. I believe it's either ignorance on his part or just a response to shift the heat to the carriers, which in many cases they are at fault when testing/releasing updates on their subsidized phones.
I just hope to get 4.2.2 to do away with the option bar in some apps and the camera improvements. If the update is not released at the end of this month, I will change my CID and other stuff to get it. I can wait, but it's been a reasonable time now and the update is nowhere to be seen yet.