Not to defend Donny, but I've known him for many years through forums, phone calls, etc. and quite frankly I've been somewhat concerned about his well being due to the tone and temperament of some of his recent posts.
Going back and reading his initial response - which he has edited to explain himself - I had the feeling he did not know it was Randy playing and in his initial response seemed to be chiding the audience for not paying attention to as he said "this great song and performer" ...
FWIW ... which may be nothing ...

And I fully understand Randy's reaction and response ...