I'm gonna sound like an ***hole saying this but what did you expect? The average melee player hates Brawl (myself included). Why would you support something that you hate?
There's a difference between not supporting something and trying to actively destroy something.
From my experience in my own region the average Brawl player hates Melee, and Project M even more, (myself not included, as I like all Smash games) and are happy about the Apex 2015 line-up. But they don't try to actively sabotage the games, hell they'll even play the games with people still.
Even though I think TreK is over generalizing the Melee player base, there is some truth to it still. Hell, IIRC, during Apex 2014 some Melee players started chanting Melee during the Brawl GFs while they were still playing, which is just downright rude, but also, IIRC, HungryBox also attempted to hype up the Brawl GFs which is cool.
And to restate my first sentence. There is a clear difference between not supporting a game and trying to destroy a game.