That grenade wouldn't have done anything...it's pretty much impossible to escape from the stomach of one of Karbo's nagas. However, that girl got lucky; due to a quantum fluke, she ended up escaping from Crisis's stomach-as a naga, however. Suffice it to say, she's a bit grouchy about the whole thing...
Karbo and a bunch of other people do a lot of these, but Karbo seems to be the patron deity of soft vore, at least on DeviantArt, and the world called Felarya is the holy land of it. Personally, I should think it would be easy to get around this sort of thing. Killing a naga isn't unheard of, especially since some of them aren't this huge, and obviously naga stomach lining is immune to their digestive enzymes, so killing a bunch of small naga, or capturing a few and breeding them in captivity, filling their brains with narcotics and synthetic hormones and such, and then harvesting their stomach walls to extensively study with the purpose of creating an advanced polymer body suit that would allow a human to survive being swallowed by a naga, sounds like a plausible idea to me. Humans can be clever bastards when they aren't being nice.
