Are you suggesting that you disagree with the author's thesis and that iron wasn't a contributing factor or the major one?

Yeah, the timeline just does not make sense. It makes more sense the other way round that the collapse made iron more appealing.

Yes. Iron wasn’t a contributing factor.

Iron was already known to civilization during Bronze Age, but they didn’t know how to make it hard. Hence Bronze was preferred.

After, and because, of the Bronze Age collapse they started funding out how to make iron useful.

Think about it, why did the humans in Americas never went through Iron Age? Because they never had a Bronze Age collapse.