I will admit that save for a few legacy projects that still use Fusion Tables I don't actively use this script anymore -- hence no real development or maintaining of it.
Something changed on the authentication end a while back it seems, and I can't vouch for whether this script continues to work or not. I know that once I enabled two-factor authentication for my Google account this script stopped working.
I've added a couple potential solutions here, but would welcome someone -- Google or otherwise -- to offer a long-term maintained solution.
Thanks goes out to John McGrath who did the bulk of the work in making this script happen.