Walking around at night is a legitimate reason for someone to call 911 on you? J.J. becomes more and more ridiculous with each post he makes.
You obviously led a sheltered life.
Someone at night, walking around a neighborhood, that doesn't seem to be looking for a house or walking through, and who doesn't live there, is suspicious. It doesn't mean the person is doing anything wrong, but it is suspicious.
You said it justifies calling 911. Not "it is suspicious," but that it's a situation requiring police intervention.