Just have to comment on how bad of a response this is. Asking for clarification conveys uncertainty, killing your bit's momentum. You're trying to convey overconfidence, so you decide what people mean.
Although personally I think Child Star's comment was unambiguous enough to be a good punchline. It could be taken multiple ways, but in this case there's enough context that the audience shouldn't get distracted trying to figure out which joke he's making. The momentum has already built up a meaning for them. It'd be best to not respond, and let the audience interpret him however they find funniest.
If anyone else threw out an easy hook, you could pick it back up, but trying to force a response here just makes the bit drag, and weakens the impact of his comment. However If you really want to get the last line, I think the only thing that would work here is an image. Like something with Gaston, or a Jurassic Park sunglasses gif, to try to solidify the interpretation. Or rather, convey that that's your character's interpretation, regardless of how [the audience interpreted how] he meant it. It creates emphasis if they saw him as expressing awe, and juxtaposition if expressing disdain.
I'm usually not a fan of that kind of thing, though; there's not much wit, especially when people rely on the same overused images. But if you got a good, expansive bank, and know how to use it, then it could work.
