That makes no sense at all unless syncing is an account wide setting instead of a browser setting, and it's pretty clear that this is a browser setting. Bob could have syncing enabled on his primary computer, log into gmail on Alice's computer where it then logs him in to her browser but without syncing enabled, and then Alice can later on come in and enable syncing by hitting the blue button.

Frankly it sounds like what Google should have done is created a better security system rather than a better notification system. This solves nothing, creates more problems, and pisses people off at the same time.