Maybe they had diverted from a rig before landing with an incorrect gear indication and at the alternate they didn't have enough fuel to get back to Aberdeen. If they could have gone direct to Aberdeen I imagine they would have. Didn't take a lot of thinking through but I agree that your theory of hidden information, conspiracy, spinning yarns is far more sexy 212.
So they refueled whilst light on the wheels and pulling pitch, and it was safe enough to disembark the passengers but not to reload them? No conspiracy theories there - just some apparent odd logic and safety behaviours.