Oh, banned him? Don't move too quickly, you might get dizzy.

Wakefield arguably assaulted his patients (most of whom were children, IIRC) when conducting his research. What do you do with people who arguably assaulted someone? You get the Crown to make that argument. Why didn't that happen?

Also worth noting: according to the logic upon which the British system of government is based, no lesser a party than God Himself put a major believer in homeopathy on the throne of the United Kingdom of Great Britain and Northern Ireland.