If I recall correctly, when she said that with a puzzled tone, I just pointed out that they were probably in the same or similar union. I mentioned the extortion letter the three LEO and the firefighter unions had sent (with the teachers’ union) to those businesses in Wisconsin. Her face just dropped in appalled understanding.
When there is a police union, it is not necessary that individual police be in political/ideological agreement with the union.
It is only necessary that the individual officers understand that it is the union that will protect their jobs if there is any issue with their jobs (officer-involved shooting, excessive force charge, etc), and that this protection is conditional upon the officer not pissing off the union hierarchy. As such, it sets up a potential dual command structure (union vs official police command), which is a very bad idea.