So what does the UCMJ say about this?
What Active Duty Members Can and Cannot Do
Cannot - Participate in partisan political fundraising activities, rallies, conventions (including making speeches in the course thereof), management of campaigns, or debates, either on one’s own behalf or on that of another, without respect to uniform or inference or appearance of official sponsorship, approval, or endorsement. Participation includes more than mere attendance as a spectator.
Cannot - Use official authority or influence to interfere with an election, affect the course or outcome of an election, solicit votes for a particular candidate or issue, or require or solicit political contributions from others.
Cannot -Allow or cause to be published partisan political articles, letters, or endorsements signed or written by the member that solicits votes for or against a partisan political party, candidate, or cause. However, letters to the editor are allowed.
Cannot - Serve in any official capacity with or be listed as a sponsor of a partisan political club.
Cannot - Speak before a partisan political gathering, including any gathering that promotes a partisan political party, candidate, or cause.
Cannot - Participate in any radio, television, or other program or group discussion as an advocate for or against a partisan political party, candidate, or cause.
Conclusion - He is breaking the law.
Check out 35, I doubt he is actually is or ever was a service member.