I did set everything to metered. That's how I finally stopped the updates. My point though was that MS doesn't consider very many non-mainstream cases.

One study says nearly 7% of all internet users in the US use a satellite connection. These are slow, and almost always metered. That is a lot of people getting surprise hammering of their connection.

While I’m not familiar with the equivalent features in Windows I believe MacOS can do this, you can have one machine share the updates to the others on your network. The feature is now even in the non-server version of the OS too.

You can cache iOS device updates with this mechanism as well. I’ve never bothered as I’m fortunate not to worry about metered bandwidth, but it seems like a nice feature if it works as advertised.

https://support.apple.com/en-us/HT204675

So, at best, that would have cut his data usage to 25%. I don't see how you assume this would've solved the issue when we're taking about such a massive update of an OS.