It's blindingly obvious that Mr Blonde was using "95% of the time" as a colloquialism for "the vast majority of the time". Obviously he is not referencing a real statistic
Especially as he didn't even claim that "95% of people detained by police were convicted of doing something wrong." So either you have completely failed to comprehend what he was saying, or you are seizing on his linguistic ambiguity to deflect from the point he was making.
the guy was riding a scooter - in the general scheme of things no real harm done. it's not as if he had just knifed someone or set off a bomb or beat up his wife. so OP didn't know who was in the right or wrong.
i also believe the police officer tried to detain the person and they simply didn't want to be detained.
he was then making the judgement call that the police officer was in the right even though he had no idea what was going on, could be an illegal detainment. police officers are human. humans can make mistakes and you do have corrupt coppers out there too. without any facts he shouldn't be intervening when the guy has caused no harm to anyone bar the person detaining them and in that instance has used just enough force to stop them detaining him.
all he had to do was let him go. then chase it up later when he had his fellow officers with him or send out an APB and request back up. he had no idea who was in the right or wrong and it's being automatically assumed the officer was in the right with no facts.
i would like to see what OP had done if there was no police officer. but a civilian trying to stop the guy with the scooter. would he have helped? i seriously doubt it. which again shows just because they are a police officer they must be in the right and cannot possibly be wrong.
i had a police officer who i had asked for help state that x was y. I then read out the law to them stating x was x and they then tried to use an excerpt to say they had reasonable cause. i then had to read out to said police officer reasonable cause in such circumstances is for as an example emergency services cutting someone out a car to save their life. therefore said person couldn't get emergency services done for vandalism for damaging the car as they had reasonable cause to damage the car; to save the persons life who was trapped in said car. but if some yob decides smash your car up to get into it isn't excluded under reasonable cause like emergency services are. officer refused to listen when pointed out they were wrong on both accounts until i asked to speak to their boss. who fully agreed with me.
so you can't assume they are correct and know the law.