I am sure there is more to this than is being reported, particularly as flight ops in Karachi approved the request (and subsequent delay). The fact that a Boots butty wasn't good enough and the caterers had to get a sandwich from a hotel suggests a specific dietary requirement. Nut allergy perhaps? Gluten intolerence? Diabetes?
Hats off to the pilot. I'd rather be delayed a couple of hours than comprimise the in flight health of my pilot...