If the police had followed procedure, he wouldn't have been standing. This was obviously done on purpose because they know what happens in the back of those transports when you're not in your seat with a seat belt on.
They DELIBERATELY set out to injure him if he wasn't already injured.
The only thing "obvious" is that he should have stayed seated. If the prisoner is resisting, putting him in a seatbelt would have required even more force. You would have cried over that as well.
You have no proof anything was done "deliberately", as usual.