Not trying to be snarky, bu what part of "No Divine Power Source on Athas" surprises you about not having paladins in Dark Sun at roll-out? Will they add it in? Possibly, but this one doesn't surprise me at all until house rule support is in.
I'm not sure I think they need to support house rules past stat differentials and feat allowances. The tool is probably best served for supporting their stuff and not trying to be able to add much house rule goofiness in. I'd say if you want to allow a paladin in Dark Sun, just make it a PHB one and re-skin it since that's what you'll have to do with a Paladin anyway.