It occurs to me long after I start that I do not, after all, have to make him your basic Flying Brick: strong, tough, able to fly. Maybe. I added a few quirks like being invisible to supersenses (he's hiding after all) and absolute direction because it produces irony in a certain scene.
I look at what I want to steal: he has to be able to break free from the people holding him captive (using such basic things as drugs, bonds, and locks), and then be able to overpower his captors for citizen's arrest. (Different times, though that hardly matters.) But not able to prove his case in a court of law. (Which will require that there not be sufficient people who can force people to tell the truth, or know when they are not, to deploy to every courtroom. At least, not sufficient such people who are trusted by the authorities. Insufficient powers is probably better for the story than corrupt authorities or difficulty proving they are trustworthy because it would distract.)
A basic brick would work just fine, and the very fact that it's kinda standardized would keep it from distracting from the other elements of the story.
Maybe I should work out his job while he's in hiding and the way that he finally (with some help) brings the villains to justice to see whether some different power set would work. (Perhaps fireworks. It would fit with the job, if my muse's current notion works.)