There is no such thing as a "cosmetic" crack in aluminum. If it's cracked, it's structural.
But that doesn't look like any crack I've ever seen in aluminum. I strongly suspect that's just a paint scratch. If you're really worried about it, you should remove the paint from the area and take a hard look at it (I'd suggest taking it to a shop, but most shops are staffed by people who don't know the first damn thing about bicycles, so...)
Oh, and yes, aluminum "just snaps". That makes it a bad material for forks, IMO, but then I've been accused of being an old codger.