Savage is right about that, but with the way he rants and raves, I'm not sure he can call anything a mental disorder.
The man is Mike Weiner. The character is Michael Savage. They share one mindset but two personas.
The rants are part of his act - if you listen closely you can sometimes hear him laughing during and after them, or trying to contain laughter.
In any case, to the extent that's not clear to folks, you are correct: the character of Mike Savage does undermine his message on occasion.