He just made himself look like that he had something to hide.
Just cause he knew a bit of legal jargon does not mean the police cannot question him.
If you watch police docs on TV alot of their arrest are made from good judgement and years of experience on random stops.
Calling the police pigs is not gonna help your cause and they had every right to make his life difficult.
If that was the US he woulda been on his face with a gun in his back.