He reports doing plenty that would unreasonably "justify" the response he received. The causal void that you object to (which would shed doubt on his story) simply doesn't exist.
Well, the guy definitely doesn't deserve all the followup treatment that he's rightly complaining about, but about that particular single episode it is quite clear - if you're given a lawful order to not hang around i.e., cross the street; for whatever technically valid reason (and not disturbing 911 ops == not hanging around == not only a technicaly valid, but a very very valid reason) - then there are two options:
a) you comply voluntarily;
b) you get made to comply;
c) there is no option c. (a) and (b) are both reasonable options, allowing to not comply is not a reasonable option.
Except when the order is not lawful because the person is not "interfering" in any meaningful way, that is. Police absolutely do not have carte blanche to dictate what someone must or must not do outside of specific, limited circumstances.
Not that it matters, because the behavior demonstrated here and the current climate of the justice system (i.e. he-said-she-said vs a cop, you always lose) means that those limitations are mostly invalid. Police can order you to do whatever and if you decline, knowing that they have no right to say such a thing, you'll just get hassled and imprisoned anyways.
If the police order you to do something (that doesn't harm you) that you believe they shouldn't order you - then you shouldn't decline - come on, you should comply anyway and then dispute the supposed rights violation afterwards to find out which of you actually was right, given the details of law and the particular circumstances.
They probably take things safe as a matter of policy. Imagine that the bystander was actually a murderer who got interrupted. If they let him hang around and he managed to finish the job there would be lawsuits to kingdom come and the cops would be vilified. There is just no way to tell in a situation under pressure, so the prudent thing is to do the safe thing and remove the unknowns.
I think there's a good point here. The police don't know what happened, only what some complete stranger told them. For all they know, Partensky is the one who knocked the bike down, and then terrorized the victims into keeping quiet about it.
I don't condone the behavior of the police in this situation; what looked like a bike accident in all likelihood was simply a bike accident.
The fact that Partensky did not comply with the order to move away from the scene is disturbing and I don't remember it being part of the previous, heavily HN-commented version of the story.
However, as others say, he probably didn't merit arrest, solitary confinement, strip to underwear, and all that lunacy. Surely the police have more important things to do than go after some goofy slightly inebriated nerd who calls in an accident.
Actually I'm more likely to believe that they were anti-gay. He apparently is gay, and came out of a "gay leather bar". You'd think in SF of all places this wouldn't ever happen, but who knows; perhaps there's some bad blood between the SFPD and the gay community that I'm not aware of.
He admits to hesitating to follow an order, talking back, etc. These do not logically, morally, or legally justify his treatment but they certainly explain why it happened.
