This may point to the FCC letter that was posted some time ago. Something along the lines that they had to submit the GSM side of the radio for testing if they wanted to get approval. HTC replied that the TP2 will be SIM locked for all US carriers so it was not necessary.
So I'm assuming the Telus one didn't have to get this same FCC approval, so the option was left enabled.
Here we go, I thought I'd give some back up information.
http://www.engadget.com/2009/05/20/h...rough-the-fcc/