You’re more than welcome to discuss the legal standards necessary to prove a threat against the president or incitement.
Ah, can't say I didn't warn you, then:
First, incitement is not protected speech, as established under the Brandenberg test in SCOTUS case Brandenberg v. Ohio (1969). Given that Comey posted it, that's the first domino to fall. This type of speech is not protected.
Second, what Comey did is a violation of 18 U.S.C. § 373(a):
Solicitation to commit a crime of violence:
(a)Whoever, with intent that another person engage in conduct constituting a felony that has as an element the use, attempted use, or threatened use of physical force against property or against the person of another in violation of the laws of the United States, and under circumstances strongly corroborative of that intent, solicits, commands, induces, or otherwise endeavors to persuade such other person to engage in such conduct, shall be imprisoned not more than one-half the maximum term of imprisonment or (notwithstanding section 3571) fined not more than one-half of the maximum fine prescribed for the punishment of the crime solicited, or both; or if the crime solicited is punishable by life imprisonment or death, shall be imprisoned for not more than twenty years.
The intention to solicit a crime was clearly established by Comey making the post in the first place. He knew the targets of his post. Open and shut. His goose is cooked.
And so is yours.