Thank you for your post.
A popover button is actually two components; the "popover button" and the "popover". When you click on a popover button, you are opening a popover; not opening a popover button. The Help is correct that "hasFocus" is respected by popover buttons. However, a popover cannot contain focus, so this is incorrect in the Help. I have sent this information to the manager of our product documentation so that it can be updated.