There is no shift right click interaction for mobs without an inventory, excluding pets.
The untamable ones happen to be unshift_right_clickable
theres no reason to allow this stuff to work on untamed tamable mobs
Unsaddle mobs don't get basic right click interaction without the saddle anyway (otherwise would be the equivalent of taming for nontamable)
Will need to check if your the owner of a pet mob; actually no nvm you can't right click someone elses pet anyway