many years ago I had experience of this, a lad who was working for me had another window cleaner come up to him and give him some serious grief over the fact he was working his 'patch', even had this huge customer come out to support him!
He tried to approach my worker again, this time I was close by, and interjected, telling said window cleaner that if he had a problem I was the one to approach, not my employee....he smiled nicely (though a rather fixed grin) and backed down (make of that what you wish!)
Just the other day a fellow forum member I was chatting to in the local high street (not Tosh or Squeaky) told me of another local window cleaner who aggressively confronted a young guy who was touting up his round and told him to basically go away because he was touting his 'patch'.
So, so wrong, if 'J' had tried it with me I'd have...er, well, you know, smiled sweetly...I'm afraid I wouldn't have been very professional
The fellow forum member gave good advice to his colleague, basically telling him - if approached - to say that he knew where he lived and would contact the police because of his threatening behavior.
I'm a mod, so I can't say openly what I'd have done...bad form, what!
Ian