WOIN Vital Defense and Size

Howdy. The FAQ for OLD and the NEW 1.2 book specifies size doesn't affect Mental Defense, and nothing is said about size specifically with Vital Defense, leaving one to think that size should lessen Vital Defense. This doesn't quite make sense, so I'm assuming this is just an oversight right? At the least, large creatures shouldn't be worse at resisting poisons, and most likely the size chart should be kinda reversed for Vital Defense. What's a barely effective dose for a large, or enormous, creature would destroy a pixie.

What's the official word?

Thank you.

Vital Defense is not affected by size.