The problem with that answer is that you don't need to add theft as a motive to make things make sense. "Feral dindu chimps out over minor disagreement" fits the pattern in a very general sense, especially when you throw in rival schools in a competitive environment. Sure, it's possible he was caught stealing, but it's not necessary to add that to come to a plausible explanation of what happened; some non-theft explanations that fit the general pattern would also be:

• He was there to hassle the rival school
• He was there to try to meet/see/hassle a specific person he knew
• He really did just go to the wrong area

While "he was stealing" is, in general, a strong possibility, there's just not enough information known to rule out other options as well. I mean, you could also say "actually, he was there to creep on so and so's girlfriend!" and that fits certain stereotypes too. Doesn't necessarily make it true.