Comment by khafra

That's why that was the least important objection, independent from the second, and only intended to address the "magic" claim, by showing that microscopic self-replicators already exist.

By analogy, consider how you might respond if someone claimed that there's no possible danger from pocket-sized projectile launchers, because they would require some magic means of propulsion that didn't depend on a taut string attached to a long, flexible arm:

You could reply that atlatls can launch projectiles without using a taut string. Atlatls are not pocket-sized, but they are sufficient to establish that projectiles can be non-magically launched without a full bow. You could then go on to describe a sling, or derringer; and these would not be invalidated by your initial objection to the "magic" part.