I'm not saying you're necessarily "wrong," but bestiality as a metaphor for scatting is a totally overused cliché. It's right out of the jazz critics' standard lexicon, Jazz Hack! And think about it: If you absolutely have to attack singers so viciously, you can choose from a plethora of crimes against humanity that are far more fitting and descriptive. "Senseless slaughter," "unimaginable atrocity" and "inhumane torture" are just a few examples that readily come to mind.
Use your imagination, and I'm sure you'll find more appropriate, creative imagery. But, I beg of you, from the bottom of my heart: Show a little sensitivity and leave my animal friends out of it, okay? And I do mean "friends" strictly in the platonic sense.
Have a question for Mr. P.C.? Ask him.