It'd work much better in this case, but there's time to learn that. He's keeping Mort, after all. He doesn't have to put on a show of his reaction, sighing and moaning musically at Mort's petting. After a few moments of being spoiled he props himself up just a little on one elbow. A little more pressure between them, and he can add his hand to Mort's at the same time he adds friction and proximity to pheromones.