Probably because the police are sick of being the bastard children right now and have the right to speak up for themselves. Just because we're a "public servant" doesn't mean we can't have an opinion on the matter too. No one person's rights are more important than anyone else's, they're all equally as important. The police unions can speak out against this situation if they'd like, it'll amount to nothing, they simply want the NFL or the 49ers to condemn what he's doing on some level. A Chief of Police is not going to allow his/her officers to not work security at these events to make a statement. That spells career suicide for that Chief. I'd be shocked if it ever happened..............
There's nothing at all wrong with them having an opinion or speaking out about it. They should. I'm only talking about the actual action they're suggesting if it happens.
I felt "meh, don't care" about the not standing for the anthem thing, but the socks show he's an idiot.