This is horse$hit. I worked in NY State Corrections, and wrote the newspaper all the time complaining about Mario Cuomo, as well as the court system. I never got any flak at work about it because I was speaking for myself, and not as a representative of the department. At no time in his letter, did he claim that he was speaking for the police department. For them to put him on leave for writing his own personal feelings and beliefs in a letter to the paper is an abuse of power, and whoever made that decision should be put on leave themself.
He insisted on signing himself with his rank and employer. Not smart if he wasn’t looking for trouble.
I remember, once upon a time, when there was an absolute and unconditional right by everyone to be protected by arbitrary and capricious actions, and abuse of power by elected officials.
That was and continue to be protected by the First Amendment.