I think for the most part people are well served by being told that they should simply say "no" to requests like these. The article has a different framing, that Californians should instead feel angrily but passively victimized by the process, which is I think not productive.
Sure, people should just decline to share any information with police and many police won't push the point because it won't play out well. But some portion of the desirable assignments will flow toward those eager beavers who most assiduously supply the desires of the brass for more information. Legalities are one thing, the incentives and internal dynamics of the police department are something else, and they don't always line up neatly. Furthermore, not all police officers are rational utility maximizers who base their decision-making on optimizing their future wellbeing.
The gist of the article is not 'you're being passively victimized again, oh no' but nor is it, as you point out, 'they have nos uch right so don't be fooled.' The news here is that LAPD management have instituted a policy of maximizing data collection for pre-emptive surveillance purposes, which is something quite different from individual cops being overzealous or prosecutorial standards having shifted.
I think it's reasonable for the writer to be descriptive rather than prescriptive, and that it is not his job to act in loco parentis or in loco advocatus.
Also I think tptacek’s core point holds. Scarcity is the civilian’s best friend: scarcity of LEOs, scarcity of their shift hours, and scarcity of their time to collect some info which has absolutely zero bearing on their current case.
No doubt some LAPD gang unit officers may request this data more frequently from suspected gang members (even if it doesn’t sound like an optional request), but I tend to think tptacek’s suggestion that this article could have been better written by informing the reader when they are legally obligated to comply with police requests and when they can be denied without increasing any legal liability.
My impression is that it's all about negotiating the interaction without winding up in a contest of your rights vs them doing their job. If it goes that way, it seems like "this guy was being a real asshole, boss" is all it takes from the officer for justification.
I guess, on the advisory front, tips on non-escalatory language are probably the biggest win.
https://www.justice.gov/crt/deprivation-rights-under-color-l...
Unfortunately, prosecutors are chicken shit when it comes to criminal cops.