The delay is likely due to counterterrosim teams and other intelligence agencies, digging deep into the manifest, and the male. It would appear that this male is just a mental patient, so likely not on any watch lists, which would cause some delay while those behind closed doors are trying to sort out who he is, not only that, any other connections he has on board. Not only that, digging into his past. Takes considerable time if he is not known. Have they missed an extremist who has gone un noticed, that becomes very problematic and concerning if true.
Operation Silves was a reminder around those who can slip through the cracks, huge alarm bells for the above teams if this male had managed to sneak through with an explosive device. Just another reminder about the continued risks this industry will always face, will always be extremists looking for opportunities.