I'm pretty sure that David mentioned something about how much work and time goes into merch, and that it's more trouble than it's worth. Especially considering that David would likely end up being the person designing the stuff, and he's already working two jobs, and merch would take valuable time away from game assets, yadayadayada... Too lazy to look up where that was mentioned, but I'm 90% certain it was.
But jeez, all us seem to have just got the game after that TB video it seems XD
That's how I found it. I'd never heard about this game, and after watching the video I realized that it was the game I'd been searching for since I was a kid.