I've been lurking for a bit, but I just wanted to say how much I personally agree with that.
I absolutely think that making Martin a less sympathetic victim is the end goal for far too many people. IMO, that is the primary reason why people argue so hard against his status as a minor, and it is also why his height and weight appears to be in such great dispute. For example, the police report puts him at 6'0" and 160lbs. Yet I've seen many posts that refer to him as taller and heavier - I had a recent discussion with someone who insisted Martin was 6'5" and weighed 190lbs. People want Martin to be bigger than he was because that makes him a more imposing figure, and makes Zimmerman's claim of a struggle far more dire.
IMO, people aren't looking for the "truth," or "accuracy" when they insist that Martin was not a kid, or make irrelevant claims about his school record, etc. What they're looking for is justification for Martin's death, and reasons to absolve Zimmerman of the shooting.