Though he was doing wrong.It's a shame that the OP Bobbies didn't have that attitude with the security guards?
"I understand what you're saying, but you have him recorded on your CCTV, he's known to us for doing this, just ignore him, he isn't actually doing anything wrong. FYI, I have much more important things to do than come down to your shopping centre."
If they got to the point of arresting him and then watched his footage they would have found that he was filming into the shopping centre, and was lieing when claiming that he was only taking photos of the sign outside the shopping centre until security came out.
It’s hardly major crime, but shopping centres are protected (due to bombings etc)
However ultimately not a lot would have happened to him.
Your drugs evidence was circumstantial - there are some people who do actually use bongs (water pipes) to smoke flavored tobacco.
The white powder is very likely to be drugs, but wasn’t worth their effort