US police and prosecutors have a track record of bad faith prosecution.
I also think you're losing perspective: it was just some nobody at the local police station investigating a theft of jewelry from some old woman! I bet it would have been totally fine if he'd popped in and chatted to the detective in question.
Reality is a lot more complex than your world perspective.
The general advise for everyone is: cooperate to the extent required by law, but don't say anything beyond that unless your lawyer is present. The police are not your friends, if they want to talk to you and you're not 100% sure it's because you got robbed or saw what happened and are obviously and exclusively treated as a victim/witness, they can and will use anything you say against you. Their incentives are solving cases, not serving justice. Their KPIs aren't destroyed if it turns out they went after an innocent citizen, and if they succeed in building a case against an innocent citizen, they are still rewarded, because it does not matter whether you are innocent, it only matters what the judge says you are. The police are not your friends.
You shouldn't drive a car into a wall at 60mph, because the risk to your health is too high. Driving it into a wall at 90mph increases that risk. Are you suggesting it's safe to do at 60mph because it's more dangerous at 90mph?
The fundamental problem isn't 60 or 90mph, the fundamental problem is driving a car into a wall. For police interaction, the fundamental problem isn't being white or black, male or female, it's being on the wrong side of the table.
The risk existing and being too high to make it advisable to talk to the police has nothing to do with race, and everything to do with police vs citizen. The relative risk is different for different groups (class, sex/gender, race being the major ones, in that order), but that has nothing to do with the risk itself being there for everyone and therefore the advice being the same for everyone: don't talk to the police, they are not your friends and they are not on your side.
Your words there are clear, and correct.
> it has nothing to do with race.
Your claim there was unclear (what is "it"?) but appeared to be making far too broad a claim.
If "it" is "the degree of worry that you might be falsely convicted", then you're simply wrong: race is a very significant factor in that degree of worry, at least in the USA.
I guess you believe that the baseline degree of worry for white people and black/latino people alike is so unacceptably high that the additional worry attributable to race is irrelevant. To be blunt, I think that is both unsympathetic and neurotic, and I think you might want to consider whether you really have enough knowledge of what life is like for black people in US cities. I am no expert there either, but I err on the side of believing them when they say that there is a non-negligible component of worry attributable to race.
It is the risk being too high. It's higher for a poor black man than for a rich white woman, but it's too high even for the rich white woman to talk to the police when she's a suspect. It's too high for everyone.
Please don't turn this site into a "acknowledge your privilege, heathen"-Twitter-clone. Read what people write, assume good faith, and if you don't understand something, ask. Don't just go "hey, I choose to ignore 90% of what you wrote, make up the gaps in my head and then reply to that". If anyone wanted that, there are Twitter, Facebook and Reddit.