I'd slap that calculus teacher up side the head. Seems like a pretty rude comment.
On the hand size issue, it should hurt your game. Like mentioned above, you can get lots of distance out of speed 9 or lower discs. Plus by tinkering with different grips you should be able to find something that will work fine. Sure, you may never throw a Boss 600', but either will most people with big hands.
"Thumbers are for cheaters"