> If that were true, the FSF wouldn't call it a free license.

It is true; the license gives you the source, to do with as you please, including closing it off.

Famously, Microsoft included BSD licensed tools in Windows since the 90s and did not distribute the sources!

And that is completely legal. If you want to force the users to distribute their changes to your open source product when they are redistributing the product, you need to use GPL.