Lol, to cut the OP some slack i'll give the first serious response, Gomi last Pride title defense was in 2006, and last Pride fight was 2007, in which he "lost" to Nick Diaz.
Henderson was signed straight out of Pride so his title was still legit, way too much time (4years) had passed for Gomi. Also Gomi losing two fights since the fall of Pride pretty much means he's gotta start from the back of the line just like all the other fighters.
Dvddanny got it right. It just wouldn't make sense for the UFC to market Gomi as a Pride champion at the time he was signed. Once the UFC bought pride and Gomi didn't immediately go to the UFC, his belt than meant nothing.