Self-Inflicted Wounds (2): Wait for the Wheel - S3-E4
Jool: Then why did I survive?
John: I don't know. You're not sick. Maybe they shanghaied you for body parts. You're the freebie.
Jool: Everything I have seen so far is despicable!
John: Welcome! To the Federation Starship S.S. Buttcrack!
Chosen answer: It's never explained. John mentions a theory that his less technologically developed craft simply interferes with the wormhole less than the "superior" Vipers, but they never make a concrete determination on that point. But we also have to take into account the fact that Moya traverses wormholes with no ill effect as well.
Garlonuss ★