I read the story like this: contract security staff member working at evening event sees two females going into the gents. Security agent may have had prior experience of or suspicion of any of the following: the two were going in to have sex (not allowed) do drugs (not allowed) sell drugs (not allowed) sell themselves (not allowed) or may have put themselves in danger (if they had been attacked in the gents and CCTV showed the security agent saw it, is the agent then at risk of being fired at the least?)
Security person then asks for ID. Asks why they didn't use an alternative facility. Is met with outrage. Explains he has been tasked with asking for ID if there is suspicious behaviour.
The two students get their story in the telegraph and the security officer gets a reprimand for not being a mind reader.
Honestly, what else could that person have done? Turn a blind eye completely? What's the point of hiring security if they aren't allowed to challenge anyone? Also, neither of the students is identifiable as a man based on outward appearance, so is the security person expected to gauge their gender identity from their aura?