I know he wasn't directly referring to wormholes, but his point ties in well with
@Buster15 trying to put constraints on what is actually possible. He says we tend to underestimate nature, nature being the physical universe, and that there's amazing science out there that remains to be discovered. There's theories on whether the universe exists on an infinite amount of wormholes connecting entangled particles, there's experiments like the delayed choice experiment on how time doesn't apply to entangled systems, quantum theory says we don't understand spacetime that well. He says in the past there have been plenty of instances where unidentified cases have been identified, they will use science to understand how life can exist elsewhere, and that they will use tools like the James Webb to help us understand better, he concludes with the quote I used. It's an assumption that he's being particularly skeptical there, I agree with everything he says.