The security guard is only the lowest performer, and he has no right to decide whether to continue to entertain guests after closing the door. He can only faithfully carry out the mission entrusted to him-maintaining the order of the library. If the library closes at a certain time, he should make sure that all the guests must disappear before this time, otherwise he may be punished or even lose his job because he fails to guarantee the regulations of the library.
I think this is a natural disaster, and everyone is a victim.
If you insist on saying who is wrong, the guest is wrong first. It cannot rain without warning. You should be vigilant and leave the library before it rains.
Secondly, the library leaders are at fault. He can command the security guard at the scene and tell him not to rush people. But no superior came out to stop it.
On the whole, the security guard should not be blamed for this.