Adding window.opener control to referrer-policy?

This bug has come to my attention:

https://code.google.com/p/chromium/issues/detail?can=2&start=0&num=100&q=&colspec=ID%20Pri%20M%20Week%20ReleaseBlock%20Cr%20Status%20Owner%20Summary%20OS%20Modified&groupby=&sort=&id=168988

Basically, Site X has a link to Site Y that opens in a new tab.  Site Y can
then use window.opener.navigate to change the tab that used to contain Site
X to something else in the background.  The user may not notice this
switcheroo and can be possibly exploited when they go back to the tab
expecting it is still Site X.

The only current mitigation is for Site X to open the new tab to a location
it controls first, use script to disown window.opener, then
programmatically navigate to the final location at Site Y.  This is very
slow.  :(

It's not an exact fit, but (if the WHATWG declines or the compat impact is
deemed too big to break this behavior cross-origin by default) I wonder
what people think of possibly adding an additional directive to
referrer-policy, "disown-window-opener", that instructs the user agent to
apply https://html.spec.whatwg.org/#disowned-its-opener automatically as it
performs a navigation.

-Brad