The PPD is unique among all law enforcement organizations. Its members are trained to put their bodies between the President and a potential attacker, "taking a bullet," if necessary. Two have done so. One was killed, the other survived. They are special human beings, whose I.D.s and personal philosophies, thoughts and utterances should be kept private for security reasons. Publicly raking them over the coals and subjecting them to undue criticism, might make their success in their mission less certain.
These employees are subject to all of the rules of conduct and similar regulations as are all other Federal employees. If anything, the rules governing them are enforced more strictly because of their critical mission. They are subject to overview form their first line supervisors, up to the Office of the President and Congress. They don't get a free pass, because of who they protect.
I am a life-long Democrat and would not vote for Trump, if you held a gun to my head. But he was the President and PPD needed to protect him without reservation, which they apparently did. I doubt that any one of them will hesitate in doing their job for a nano-second as a result of this public criticism. There are better, confidential ways of handling this type of circumstance.