Are you saying tall, light teens don't throw punches at short fat Hispanics? I've heard first hand of a sequence similar to this occurring, but in a country without guns. The kid knew he could outrun the bigger person and successfully escaped.
I've also known of a similar example, in which two fifteen year olds assaulted an older person with a belt in an attempt to blind him; and then these two miscreants concocted a story that turned the older person into the assailant. Fortunately, in this case, there was a witness.
And by the way, do we actually know the weight differential? All we have are newspaper reports.
Z said he was punched in the face and fell down. The punch is said to have broken his nose. The head banging is consistent with Z's statement and the claims of cuts to the back of his head. Z's team also claims there was a witness who corroborates his account.
But this is not my point. My point is that the temptation of trial by media is very great. The media tends to pick sides. In this case, they are clearly picking sides against Z. Hence the photos of the nice-looking young boy, rather than of the 17-year old teen.
Hey, the sarcasm in me says the journalists may want to sell newspapers and ad slots - which is why the news culture is so trivial and sensationalist.
I think we do better as humanoids thinking about casting blame when we are patient - at least until we are no longer in want of the facts. Or whatever facts are available.
I counsel you and anyone else to hold back before presuming legal or moral culpability.