You are wrong, the husband is not automatically placed as the guardian when there is a conflict of interest. The best known case that illustrated this is the Sunny von Bulow case. But there are scores of others also.
No, you are wrong!
If the husband is the legal guardian at the time of vulnerability, he remains the legal guardian UNTIL there is a court ruling to the effect that there is a conflict of interest impacting the welfare of the disabled and in turn dictates who the legal guardian will be.