I think you should report it to the police and the dog warden. They don't seem to give a stuff about how their dog behaves if they have sworn at you on the past when it has been aggressive to your dogs.
Apart from the could be a child idea it could also be someone's small dog or puppy that gets attacked and may not have an owner savvy or strong enough to defend their dog.
I personally wouldn't walk that route again but I do carry a pet corrector spray and a legal attack spray as Cherry got attacked by a Rotty and we have had a few Staffy attacks where I live recently.
When Cherry got attacked I made the owner come with me to the vets and pay the (large) bill but they only came because I was screaming for someone to get the police (the owner was walking away with Cherry oozing blood from her side). I told him that if I saw the dog unleashed and unmuzzled I would report it to the police and dog warden which I did as they still walked it unleashed/unmuzzled despite it having bitten before!

Take some photos of the bite mark. Then I would go and see the dogs owner and tell the that if you ever saw the dog of its lead and out of control again then you will go to the police with the photos of the bite. Also that of you do go to the police he will possibly have to have his dog PTS.