The prevailing theory as to why White men that are married to Asian women are generally above and beyond racist than any other group goes as follows:

White men that are insecure, or have extreme views, generally are unattractive to non-Asian women, and only are able to use their whiteness as leverage to get into relationships.

White men that have racist or misogynist views – such as white women being too liberated, will generally have outdated views on many things, and therefore go for Asian women because Asian women are famous for “defaulting” to white men (not black, Arab, etc).