what you think people are supposed to say? "oh you didn't make any effort to identify this man correctly before slamming him on the ground, its ok everyone makes mistakes though you are fine" no. that isn't how this works.
keep in mind this cop has been sued 4 times for excessive force in his 4 year career. he didn't even log the incident in his end of shift report. he was accused of punching a driver in the face and said "no he bit my fist" ( i can't even make this stuff up). how many mistakes do you believe a cop can make before he is held accountable for their actions?
police are literally people too, with their own lives, hopes, dreams, and also will to live
one guy forgeted up, has consistently forgeted up, and based on his past will continue to forget up and should no longer have his job (or even have had his job at the time of this event)
that doesn't mean other cops should take the flak for it, but i suppose restrictions will probably be added for prevention's sake