Man, I didn’t agree with any of your comments before this one, but I could at least see your point of view, but this…

You can plug in anything you want here. Now, the engineers can give their opinions and estimates, but they can’t decide it. The PM can. It’s his job to weigh the risks and uncertainties and decide on the path forward.

You are either a PM yourself or are just making shit up to argue. The PM, at best should only be responsible for signing off on tech choices. If PMs were making decisions, then we would all be using Excel as an enterprise database, documentation tool, and version control.