You have been lucky to find food on BA that is worthy of a heat indicator. I find the food both onboard and in BA lounges to be fairly bland, even when spice would be appropriate such as a chili or curry.

It would however be a good idea for EK - they often produce spicy food, appropriate to their destinations... I have overheard a few disappointed westerners complaining that the Thai and Indian options (clearly described on the menu as 'in a chili... sauce' or 'well spiced') actually contain some heat!