The writer is interested in pushing a narrative (one that I happen to support, just so that we are clear here). The dirt bike thing is slipped in with some other clearly unreasonable stuff, but I fear he is either stretching with the dirt bike example to pad out that section, or is aware of the problem but is giving those kids the benefit of the doubt an assuming that they had nothing to do with the dirt bike gangs.

Even if those kids had nothing to do with those gangs, riding dirt-bikes in a city is clearly anti-social behavior that needs to end. If there is a racial bias in the enforcement of those laws, that needs to end too, and the white kids need the book thrown at them too for it, but I really don't believe that the author use to get away with riding dirt bikes around in cities. That isn't standard teenager shenanigans.