Originally Posted by
Tzardok
Someone who is inside a creature's stomach has total cover against attacks from outside. He can't be targetted, and emanations or bursts can't get through to him. Now some emanations have descriptions according to which they can pierce barriers (detect evil, for example, is called out as being able to go through stone unless it is too thick, but not through lead), but antimagic field is not called out as working that way.
Because creatures and objects are different things by the rules. If you need an explanation, blame it on souls/animi/other animating forces. And it's not about "someone". It's about "some creature".