While systems and institutions have an extremely strong effect on society, projecting the perceived net-effect of an institution onto the intent of every individual participating in that institution is absurd, and your implied true version alignment isn't any better.

I don't have to project anything onto anyone. Cops and their "unions" speak their intentions all the time, and it's always vile.

I urge you to step back from tribalism and ideology and view people as individuals, even if you find their flaws glaring acknowledge they have their own deeply complex lives.

I'm not being tribalist, e.g. I acknowledge the possibility that individual police officers can do decent things outside their police jobs, and even that police officers can change for the better (by quitting their jobs and working to undo the harm they've done). I'm being, openly and assertively, collectivist in my analysis of police. Policing is a collective institution. It's not just a bunch of shitty individuals running around being assholes (although it certainly includes a lot of that.) It's their net effect, their superadditivity in the space of "doing the legwork for the bourgeoisie", that makes collective analysis work here.

What's the point in generating conflict and driving people away?

Safety. Police are dangerous individuals and need to be deradicalized before being allowed in safe spaces.

Will starting fights with cops help you make the world a better place?

Yes unironically, we need to fight them like they are an occupying military, because that's what they are.

On a practical level, what good does it do to conjure opposing ideological specters?

It's not just ideological, as cops are mostly too ignorant to internalize a complete ideology. If by "ideological spectres" you mean "lines in the sand", then yeah I actually do think it sometimes helps to draw lines in the sand, in particular to separate ourselves from dangerous people, like police.

Surely it's better to work together where you can and steer clear where you can't?

We literally cannot work together with police on a single issue. We are diametrically opposed. And even if ideologically we found common ground (which we won't, but just for the sake of argument), police are dangerous to be around.

Perhaps there are instances where it's appropriate to demonize someone for a specific action they've taken,

For example, joining a policing organization

but do it consciously as targeted tactic to remove especially egregious and obvious threats, never as blanket ideology.

That's what we're doing, but you reject our perspective for some reason.

Please, I beg you, read at least the first few chapters of Our Enemies in Blue by Kristian Williams when you get the chance. Policing is such a vile institution and I seriously doubt you would be writing like this if you understood its history.