There wouldn't be much point. Despite what you might see on television, the threshold one must meet to effectively employ an affirmative defense based on mental defect, is VERY high. The likelihood of the Dr. prevailing at trial with such a defense is zero. And, let's face it, such a defense would undercut the very political point he's apparently willing to forfeit his career and his profession to make.
Like I said, it's an awful lot to throw away, to receive nothing in return.