Considering the upcoming movie already notoriously has a scene featuring the Disney Princesses playing up their various personalities and stereotypes, the lack of tolerance for a Kylo Ren joke might seem like a surprise, but the directors don’t seem too bent out of shape about being told “no.”
Disney apparently has pretty strong communication between departments, as Rich Moore said the creative team respectfully went to Lucasfilm with the original idea, whereupon they were promptly shot down.