Tribes nailed it in the ten ring.

Every law enforcement, security, military department I'm familiar with has similar departmental rules & restrictions about badmouthing the brass/management/department and how it's run, by the ranks in public. You may be within your civil free speech rights, but they'll hang you on departmental rules & regs every time. On occasion this can even be justified for reasons of security, but for the most part Police Commissioners,Generals,Governors, etc don't like being shown up in public for the incompetent horse's patooties some of them can be.

I'm surprised Chief Wiggam hasn't tried the "HomeLand Security" end run yet.