Not a good idea for people to carry guns on aircraft. Air-Marshall's do it, but they are specifically authorized and have special training.
and that day at least one of the officers had the word police on his uniform.
Which tells me that so far as anyone knew, they were a valid legal authority.
So are they being charged with impersonating police officers? If they aren't officers and then pretend that they are, that is a criminal offense, and one which cannot be ignored by law enforcement.
City Proposes Removal of Word 'Police' From Aviation Department Security
Your link doesn't work. Interestingly enough, the title of it implies that it is normal for the word "Police" to be on the uniforms of the Aviation Security Department.
In fact it is so normal that the City has to propose to remove it.
City Proposes Removal of Word 'Police' From Aviation Department Security