According to the article about the missing bike, they did not report Shawn's bike missing. Another bike in the neighborhood was reported missing. After the officer took that report and was leaving, someone told him about Shawn's situaton. The officer then went to speak to the "Devlins." Notice plural?
Oh, gosh, that came out wrong. Shawn's situation = Shawn's bike having been stolen.
Even if that's correct, that another bike was missing and the cops were told that Shawn's bike was missing, too, which led to them getting a good look at him but not recognizing him and not rescuing him, that MUST have cemented in his mind that cops would be no help.
Also, Devlin's boss at the pizza place said the neighborhood cops KNEW Devlin...he waited on them constantly and knew what they wanted to order even before they said it.
Imagine how Devlin could drive that point home to Shawn...I know the cops, they are my friends, they will believe what I tell them, they will not believe a kid like you, yada yada yada. If you say something bad about me, you'll be the one to get in trouble, not me.
And on and on it went...
You are correct it wasn't Shawn or Devlin who called in to the police station to report the bike stolen. The cop was already there at the apt complex following up on another report of a different stolen bike.