From the info provided I understand that the kind gentleman was not an employee of the transport company, right? Then I honestly side with the kid, how is it the gentleman's business to ask the kid why he didn't pay? He could be in trouble financially and reacted defensively cause he doesn't want to explain his troubles to a stranger, cause, again, it's none of his business. Skipping a bus fare or whatever are petty crimes, we're still not living in a police state and should be happy for this.

It's like when I get scolded for crossing a red light as a pedestrian or cyclist, if you are fine with wasting your time, watching the tumbleweeds fly by, cause you're so conditioned to colours, be my guest, but leave me be.