Yes, Cotto has Cotto promotions under TR with UniMas and HBO. And from what was said in interviews is Cotto would only fight at 154, but Martinez wanted that fight so Martinez asked for the catchweight. Martinez disagreed with fighting at 154 cuz he can't run like that anymore. Both Cotto and Martinez said it.
Here you can see originally the fight was set for the full 160:
Martinez vs Cotto negotiations include no catchweight, full 160 pound limit - Bad Left Hook
"Martinez adviser Sampson Lewkowicz says that there will be no catchweight for the fight if it does happen."
But then Team Cotto including 159 catchweight in the contract:
*Martinez's advisor, Sampson Lewkowicz, was somewhat perturbed by the path of the negotiations, which included the fight being billed "Cotto-Martinez," and the contracted notion of catchweight of 159 pounds.
"Sergio always makes 159 pounds, easily. So when we saw that they wanted to negotiate 159 pounds as a 'catchweight,' then I can call that 'stupidity,' because Sergio is always at 159 when he's in shape. I don't know what their agenda is to call it a catchweight," said Lewkowicz.
Miguel Cotto-Sergio Martinez done for June 7 at MSG - Ring TV
"Regarding the catchweight, the 159lbs limit was something just to get under Martinez skin. Martinez felt disrespected and I think that is going to make it a more intense and interesting fight" - Bob Aurm