I disagree. The linked google page ( https://sites.google.com/site/bughunteruniversity/nonvuln/op... ) makes the argument about the mouse hover tooltip, as if that is the only risk of an open redirect.

This is much worse, this is a redirect after login. You just logged into google, you entered your 2FA code, and then the next site you arrive at you damn well expect to be google.

Additionally, the OP is correct in that there is a whitelist bypass happening here. Why bother to whitelist *.google.com/ if you can bypass it with a redirect.