Thomas,
That post DOES apply to your case.
The problem with expired passwords is that they are no longer valid, and that is exactly your case when the user password has been changed somewhere else. The notebook caches Windows logon information (user/password) and uses that information to log the notebook to 802.1x. But the stored password is the old one and will be rejected by the DC because it is no longer valid.
Check this article about SingleSignOn:
https://technet.microsoft.com/en-us/magazine/2007.11.cableguy.aspx
If you have Single Sign On enabled (probably), Windows will log the notebook to the 802.1x protected SSID before asking for Windows user credentials.
Which credentials will it use depends on whether EAP MSCHAP v2 is configured to use stored Windows logon credentials or not.
If it is configured to use stored Windows logon credentials... guess what? It will use the OLD credentials, because those were the ones used the last time there was a successful login. If you uncheck "Automatically use my Windows logon name...", 802.1x should ask for username/password each time it connects to wireless.
The alternative is to connect the notebook through a wired connection and login with the new password, which will refresh the stored credentials. Or create the "remediation" SSID with no security indicated in
https://community.extremenetworks.com/extreme/topics/reset-expired-password-over-wireless