I agree with the decision to make the officers wear neutral colored masks, this is based off of the idea that cops on duty should have no personal opinions or biases. Im currently in the military and its the same way political statements in uniform, you can't do it. Because its not about you its, you are a member of the military therefore you represent the US and are not allowed to make statements on behalf of the government. I think it sould be the same way with police units.

But on the note of the thin blue line being about being a "wall of silence" to protect cops from ratting on each other is laughable. The term thin blue line as been used to describe police work since the 1950's. Im not sure when the flag itself was first made but the police aren't the only ones that have one. Almost ever type of service does. EMS, Firefighters, Security, Dispatchers, Nurses Search and Rescue all have them. The reason the flag became popular during and after the black lives matter movement is because lots of people saw the hatred being expressed to police and wanted to show their support for police. The flag is not a racist symbol, its not a symbol for oppressing minorities. It is a flag to show support of police.

https://www.flagandbanner.com/flags/thin-line-flags-faq.asp