Make I am not trying to pick you up on the individual words to be mean I just felt that there is a confusion on her about what words describe.
I could pat my colleague on the back, he could spin round in his chair and slap me around the face and say I had hit him. He would not because I (thankfully) do not work with knob heads!
Bella thank you for replying, I hope my comments were not harsh, they were not intended. 
You mention "is it possible the colleague cannot/did not understand any "banter" in the way she intended". Yet if the OP is to be believed (which I do) then this collaege uses a sarcastic manner often. So presumably he does know how to dish it out and should know how to take it.
"did her colleague instinctively react to his personal space being compromised and lashed out?" If he did would you like to work around someone like that, I would not. Is that a reasonable response?See my comment above about patting a collegue on the back.
""most worrying" I cannot remember what I referred to as most worrying and I can't see I said it to you but I may well have done that and cannot find it!
what did I think was most worrying?
"again, for the avoidance of doubt, report the incident OP!" Great advice and I totally agree with you. 
"as a self defence reaction with millisecond speed then it would be difficult to apportion blame when malice isn't a factor"
Yes of course it is a shame to apportion blame and all but someone is to blame. What if she had a cup of hot coffee in her hand and scaled you?
Maybe you could apportion it as an accident (not that I would) but similar to leaving something in the walk way that someone trips over and maybe is injured because of.
I once left my bike sprawled on the pavement (as a teenager) outside a newsagent. I came out a few minutes later to find a blind man sprawled on my bike. I was mortified, apologetic, I am sure I helped him up etc, I can't even remember what happened next. But I know I would never leave my bike, or allow my kids, to leave anything in-front of a shop like that.
If we do things that hurt people but even by accident, there is still blame to apportion, but most all lessons to learn.