Poor dog. Sounds like a rushed and possibly convenient decision.
My cats routinely assault me, my wife and the kids for crimes that range from ‘not feeding them quick enough’, ‘sitting on the wrong part of the sofa’, ‘stroking them’, ‘being near them’, ‘moving them’, ‘walking past them’, moving yourself’ etc. There is often claret and tears. But they’re cats, it’s what they do, we accept it. Dogs growl and snap when they’re upset or feel threatened. They’re dogs, it’s what they do.
For point of reference I’ve been around dogs all my life, been bitten many times, nearly always my own fault; except for the two instances involving Yorkies. Both those little b******s can burn in hell for all I care, but they were not put to sleep.