I'd guess that times were a bit hard at the airline (they folded in 1988), hence they were trying to avoid the extra costs of diversion.
In a similar vein, I once watched a 1-11 launch off 05 at Teesside looking quite heavy and which immediately started dumping water-meth. Everyone else was using 23, but this chap appeared to want to take advantage of a very slight breeze off the sea. Most strange, I thought.
I had a contact at the handling agent. "Oh Yes", he said, "We were a bit creative with the load sheet, us and the captain". It appeared to be tankering quite a lot of fuel.
A week later, the airline had ceased flying.