Not a witch hunt only makes sense with this belief. You try to have it both ways, i.e. Trump is under criminal investigation and this investigation is not witch hunt. But it is not his view. His view has logical consistency with his belief: because Trump is not personally under investigation, it is not a witch hunt.
His belief is the reason why he advocated in favor of turning over as many internal documents as possible and as soon as possible. His belief is also the reason why he repeatedly made wrong predictions, i.e. Mueller’s investigation would soon conclude. “By Thanksgiving,” he said in August 2017. By the end of the year, he said in November 2017. “Shortly after the first of the year,” he said in December 2017. “In 4-6 weeks,” he said this January 2018. Of course his belief is the reason why he becomes Trump's former lawyer now. Also, Mueller is American hero is because of his Vietnam service, not because of Russia investigation. That's what he meant. Don't hijack that either.