They’re right, too. Declination of prosecution is the remedy specifically prescribed by 20-07 for some offenses, notably trespassing. Whereas before this was a subjective call by a prosecuting attorney (i.e., redirecting troubled folks to get care), Garcón has made it proscriptive with little regard for the circumstances. That’s what UP is fundamentally protesting here. In case it’s not clear, they’re barking at and low-key threatening Garcón with this letter, not the police (but it’s a rather weak threat; UP avoiding LA county doesn’t impact the DA nor county much).
The two halves of American justice are often unclear and blend together. I get that it’s easy to blame the police here, but they honestly have pretty much nothing to do with it. I say that as someone who considers LAPD and LASD hostile entities in the general case, to reinforce for you that this is just a misunderstanding of how arrest and charging works in the US (it’s common).
Look up the shenanigans with the LA County sheriffs department essentially stealing property owned by LADWP to build an illegal helicopter pad near the sheriff’s residence.
Or how the county sheriff just brazenly ignores court summons.
Or look at the crazy manhunt that left several citizens dead because the LA city police didn’t want a former-marine police trainee to spill the beans on how they routinely abused arrestees.