Thunderbird back in the air after "...sign in using your corporate mobile device..." security rule by google

Locked Out of Thunderbird EMail by a Google Security Rule

The Problem

Using a web browser to try to login to my G-Suite gmail account, I got this message: "We detected an unusual sign-in attempt. To make sure that someone else isn't trying to access your account, your organization needs you to sign in using your corporate mobile device (the phone or tablet you normally use to access your corporate account)."

It turned out the User had been automatically suspended, aka made inactive, by a default google security rule.  It was a false positive, but knowing that did not help too much.

It seemed to be the same problem as described in this google support issue

But it was a little different.  Even after having admin.google.com make the User Active again, and being able to login on the usual hardware device, Thunderbird was having fits.  Thunderbird was stuck in a loop of opening the oauth2 window, asking for a 1. login to google, 2. put in the email address, 3. select G-Suite, and then --- what --- back to 1. asking for the email address.  Thunderbird ( on Ubuntu ) crashed after every File > Quit out of Thunderbird.   Frustrating.  

The Solution

In Thunderbird, use the menu, go into Edit > Preferences, Privacy, and turn on the checkbox for [x] Accept Cookies.   Then answer the oauth2 questions and instead of looping, it will ask for the password, and then go forward -- as it did before the user was suspended.