Calling the doctor a criminal is literally libel. Accusing someone falsely of a crime is, in fact, not included under the right to free speech.

In civilized countries, like Canada, hate speech is not a protected right. Peterson's blatant transphobia can and should have consequences, but in the 'land of the free,' the only thing he's technically culpable for is the libel against the doctor. But also, Twitter is a private company and can enforce their own rules; the right to free speech protects you from the American government, not from the policies of privately owned companies.