I agree with one of your points, Sisko -- it's a question of "want" for Ambrosia, and really there are better things they could be working on, I'm sure.
Plus, consider all the things more than a level editor that make each level so fun, and that aren't mass-marketable -- i.e., the splash screens, the MUSIC, the new enemies and their sprites, the special effects unique to some levels (wind, slipperiness, lightning flashes), the bosses... some of that could be put in level editors, but most of it really just couldn't. And ask yourself, how much fun would the levels most people would make be, honestly? (In StarCraft, that's a different argument than in side scrollers, I'd say).
By "generic human," I'm sure he just meant average consumer, i.e. someone who can't write letters to mum in assembly language. I don't imagine that mediocrity, stupidity, and/or immaturity had to do with what he meant, although instantly taking offense to it in what has been a remarkably even-keeled web board might not be the best idea?
Back to pulling out my remaining hair trying to get the boulder on the button in "If you can't stand the heat..." ...
------------------