After investigating this ourselves, it turns out it is true. So here is how you can revoke access, then later create an account through Pokemon.
**Warning, you will lose all your Pokemons you've already collected doing this.
In a browser, navigate to the link below
https://security.google.com/settings/security/permissions
This page will show which apps have access to your account
Click on Pokemon Go Release, then click the "Remove" button, then ok.
This will deny all future access of the app accessing your Google Account.
Now, when you use the app again, you can sign up using their our account system.