Either comcast fixed my issue in the last 10 minutes without me calling the number listed in this thread, or the steps I'm about to outline actually fixed my issue.
1. Visit maxgo.com on a desktop compouter.
2. Hit "sign in" and choose "comcast xfinity" as your provider.
3. This will redirect you to a maxgo/xfinity co-branded login page where it asks you to enter your comcast username and pw.
4. If you are at this login page, click in the address bar of your browser, you should see a massive link ending in "&forceAuthn=0"
5. Change "&forceAuthn=0" to "&forceAuthn=1", leave the rest of the link as is.
6. Hit enter to refresh the page using the "&forceAuthn=1" ending.
7. Now you can enter your comcast credentials and login.
8. Hopefully, you got the same result I did and you're redireted to the maxgo webpage and no longer the "Good News!" comcast page.
9. Post whether this worked or didn't in this thread so others know whether to try it before calling the number.