It would have stopped someone from using a phished GApps credential from logging in to Google using it, though.
It sounds like one prong of the attack was to gain access to one employee's email, then use that account to send phishing emails to other employees. 2FA would have stopped that.
You're completely right. I was too focused on the fact that 2FA doesn't text you every time you log in, meaning a 2FA user wouldn't find a google login prompt without a text code requirement abnormal. They couldn't login from their own machines - that's the whole point! Silly me.
It sounds like one prong of the attack was to gain access to one employee's email, then use that account to send phishing emails to other employees. 2FA would have stopped that.