Or he saw it was a kid who potentially wanted to cause trouble (like 99% of all teenagers today if you believe everything in the Daily Mail).
I (someone completely unqualified for security) was able to see on FIRST viewing very quickly that it was clearly just a little kid who posed no threat whatsoever.
If he can't see that then he isn't really qualified for the job he is doing. Surely it is ESSENTIAL that he can quantify any possible threats/risks very quickly, what if he CLATTERS some old Doris who wanders into The Security Bubble (TM) next?