The Antikythera mechanism is very impressive, actually stunning for the time period. Yet, it is not a "Von Neumann Engine". It cannot be compared to a modern computer; and, it is not a computer in the sense used today. I have been working with computers since 1967. I have been reading and studying the field all of the intervening time. I have made my living in the field; and, I'm an "embedded guy" who skirts the line between computers, mechanical devices, and scientific instruments
Archeologists are not qualified to arbitrarily classify the Antikythera mechanism as a computer.