I work at SIN (one of the organisations stated above, but not SIAEC) and I can assure you with 99.9% certainty that prisoners are not given work at Changi Airport. It's a bitch for people like myself who don't (yet) have a criminal record to get the airport pass approved. The Internal Security Department (our equivalent of the Gestapo or the CIA, however you want to look at it) goes through every application and does background checks on all applicants for the airport pass. When I was in desperate need of more staff and offered one candidate a position after the interview, he could only take up the job one month after the offer since all the police checks had to be done. And he isn't even getting anywhere close to aircraft.
Just to get back on track, if Cox thought that SIAEC was indulging in unsafe maintenance practices, he should not just have told them to stop it. He should have informed the police and the relevant regulatory authorities.
And Cox said he picked up on it, William Tan says it never happened, so who is telling the truth? Surely we should find out in a court of law?