Exactly... the possible permutations are endless. Only people who believe they'll pass the security checks will submit to the process, which to date has been everybody - including the bad guys. If you are part of a group planning what the IRA used to call a "spectacular" you'll do all you can to minimise the possibility of something going wrong on the day. So the first thing you do is look for the loopholes, backdoors and blindspots... and those responsible for foreseeing possible breaches have a piss-poor record.
PM