I hate to do this to such a well-written answer, but this does not answer the question. Your answer focuses on service animals, which are not ESAs; ESAs aren't trained to assist with specific tasks the way service animals are. There have always been service animals for more than just blindness (even if that may often be the trope people who haven't encountered them may think of); they can be medical alert/seizure alert trained, mobility assistance trained, anxiety trained, and more. Right now this answer focuses only on service animals, though; fleshing out the differences will help a lot!

The action in general; as cats leave kittenhood, the act of scruffing them no longer has the effect of "turning them off" and they can thrash and fight against it, which can cause injury if you're attempting to lift them at the same time.

Scruffing doesn't work on adult cats, and can cause them physical harm

Please call your vet back with your concerns and the additional information