I mean if people here/on Reddit don't find out who/where the guy is, 4chan will. That's just how it goes. Though I'm more suspecting that this is an elaborate hoax by someone with incredible attention to detail.
On Mach Rider's gender:
I know very little about the character, but look at the in-game art.
That is undeniably a male physique the likes of Captain Falcon.
Of course, there is always the "Samus" argument that it could be a woman in a suit, except that Samus was in a suit of large power armor that hid her identity, not a jumpsuit that showed muscle definition. You could stretch and say that it's a muscle suit with those built in to give that false impression, but... come on. Do you think the developers were putting that much thought and effort into it? Samus was only a woman because someone on the development team said "Wouldn't it be cool if Samus turned out to be a girl?" and that was it. I doubt the developers of Mach Rider were working on an elaborate ruse. And since this game predates Metroid, I find that even less likely.
It's not impossible, but I find it hard to believe that it's gone unconfirmed for over 30 years if this is indeed true. Sakurai could always make it true, though.
There isn't. The games unanimously refer to her as female. The Smash blog made a goof and said "it" but that's since been corrected. The only people who want to argue otherwise are just deluded.