I think that's what everyone is an agreement with. Fight night weigh in isnt fair because Cotto wont be able to hydrate to 160 and outweigh Manny.
Even at a catchweight 143, Cotto would still likely rehydrate 10+lbs over Manny, but it's still unfair to him.
Everyone wants Manny to go to 147 and disregard any advantage that Cotto would have going in at that weight considering Manny hasn't weighed more than 150 during any fight, while Cotto has unoficially gone over 160.