Hi and welcome to YT
!
So sorry for the loss of your Maggie.
How old is George? His behavior sounds very, very odd if he is an adult and I can't help but wonder what the heck has happened to him if he's an adult at this point.
If I were you, I'd obtain the help of a good trainer for George, someone who truly understand shy dogs and how to help them gain confidence. The growling thing is called "resource guarding", so I'd google that term for suggestions.