In what way was he threatened?
He was called a muppet and told to **** off.
No threat was made.
I agree he was provoked. But that isn't the same thing.
It was not self defence.
You don't need to be physically attacked to find yourself in a threatening scenario. I have every sympathy with him. His respnse was more effective than the goalkeeper who tried to mind his own business and was punched by cowards steaming in from out of his sight line.