First, from a legal stand point I think the image is very distinct from the Guy Fawkes' mask. It is a piece of that mask over-layed on a surgeon's mask with the "R3VOLution" word on the mouth.
Second, I think that the Fawkes mask can be very beneficial for the movement. I agree that it can just be whole-sale taken an used--which is why we modified it and created something new. But the Fawkes mask has HUGE brand awareness. People understand that movie delivers a message of liberty against oppression. And that message is embodied in the Ron Paul movement. Connecting these two powerful brands just further raises awareness. All that needs to happen is for someone to go on Youtube and search Ron Paul and see what this is all about.
And you didn't see the shirt? It is grey right on the homepage.