If the person in the video was a 270 pound guy on his 3rd arrest for B&E and had an arrest history that included violent assault, you'd want him to be chained to a bar without shoes while he was booked.
Aaron was a slightly built kid, with no priors, on a non-violent arrest. But those kinds of details don't filter down to the booking officer, and most police stations are equipped to handle difficult "customers", that's why there's 3 inches of protective glass between the officer and Aaron. There's no special "well he looks like a nice kid" booking room.
The police in the video appeared courteous and non-aggressive. Nobody was tased, beaten or abused. Aaron was arrested and was cuffed and detained, the same as for any other person. As they went through their processing of him, they asked him politely, thanked him for compliance, assured him things would go smooth and he'd be out pretty quick. They asked him about his medication, verified what it was, asked when he needed his next dose. In terms of police treatment of a person under arrest, this is pretty nice. Of course he's going to be handcuffed, he is in police custody after all.
They're not going to just find a comfortable chair for him and ask him if he wants to share in the squadroom's latest pizza delivery while the booking officer runs out for lattes?
This is what being under arrest actually looks like.
Standing for 23 minutes is hardly cruel or unusual. He wasn't being badgered, they weren't using coercive tactics on him, they didn't even ask him any questions about his case. It was Aaron after all who admits to walking onto MIT's property without a question being asked of him!
As tragic as what happened to Aaron is, and the feelings about it that I'm sure you and I both share on the subject. Messing around with other people's property and consequently the law enforcement the might come from that is not something you want to be doing ill prepared.
Was MIT's handling poor? Was JSTORs? There's a healthy debate to be had about that. But w/r to the police and the circumstances of his arrest he was treated about as humanly as the system allows for now.
In the end, Aaron took his own life. The same naïveté that caused him to look at a closed service door and think "that's a place I'm going to set a computer up and harvest hundreds of thousands of research papers, nobody will know" is also what caused him to buckle under the immense pressure of legal entanglement. He wasn't put to death, executed, beaten to death, tortured or any other horrible thing. He did something against the law and ended up in the grind of the system. The system, instead of treating him like a sensitive special snowflake like we'd like them to have, treated him like any of the other thousands of people it handles every day.
It's a shitty way to be treated, but if you want to be in a public fight for your principles, it's something you have to be mentally prepared for. If what you are doing might get you arrested, this is how the legal system works. Be prepared.