Perhaps there is a substantive difference between extrapolating based on past trends and probabilities, and asserting based on faith.

The imaginary guy you posit, John, is not speaking for science, but to forward a belief he has. The creation of life in a laboratory would prove that it could be done but it doesn't prove anything about what is "all the way down". He is trying to inject a buried premise (in your imaginary assertion) in his argument, but it does not stand up to analysis.

It's reasonable, based on accelerating developments since the 1950's, that the transition from non-life to primitive life will be made to happen in a lab at some point. That's just an extrapolation of trends. The meaning thereof will be an entriely different question. And even that event will be light years short of self-aware life capable of intentionalilty.

A