(Or it can be an arachnid/human hybrid, but it's probably not that.)
Webster is old Scots for a weaver.
It ought to be the offspring of a spinster, really.
Not a guy that lives in a dictionary
These days
City + Person means someone living in such city. They don’t say “from + place” because that implies origin which they try to avoid these days.
I interpret Webster Man to imply origin even more strongly than "from Webster". The noun phrasing implies long term stability, objects don't change from one noun to another noun when they change locations.
Pretty stupid to assume familiarity with random suburbs though, unless writing in a local newspaper.
A man who lives in Webster, in this case, Webster, New York. A suburb of Rochester.