I never "log in" at google. No menu shown.

But.. something Good has now come from the incident.
I dumped User Agent Switcher in favour of the HeaderControl plug-in, which allows per-site specification of the User-Agent string.

So now, I give "Unknown Linux" as the UA to google, and it has also gotten rid of their cutesy/annoying "delayed menu feature"!

Woo-hoo!