This is precisely what I talk about when I say "if you try and talk about it you'll probably sound paranoid or irrational" - this perspective can't be explained by those who don't have to live with it. It's trauma, black people are living with trauma when it comes to the police.
The police didn't do anything out of the ordinary - I didn't suggest that they did - it's the fact he knew, in that moment - his innocence was hanging on the word of someone else. There's a long history of people who are jailed for crimes they don't commit, falsely arrested, put in jail awaiting a trial date that doesn't come for months etc. If he went down the police station, he wasn't sure when he would leave.
Beyond that, peoples memories are bad - the victim of the robbery could've misremembered and said it was him - now his life is ruined, that easily.
-edit: the 'description' is often when you are black and of a similar build - which is why we saw that woman in Central Park a few weeks ago screaming into the phone that a 'BLACK man was threatening her life' she knew that was the only description that mattered.
Luckily for him, none of that occurred, but now he has to live with that experience, his relationship with the police wouldn't have improved, his day was ruined and it's a memory that will last with him. He could've easily been seen by someone he knows or works with, passerby's will see a black man surrounded by white cops and will assume he's a criminal - further stereotypes are now being reinforced. It's a cycle that doesn't end well.
There has to be a better way.