There is a CJEU judgement which ruled out EC261's involvement where there is just a transit in the EU. But this case is covered by the UK version of EC261, and so would BA passengers going from USA to India. Iberia passengers going from say USA to Cairo on a Iberia itinerary may not be covered, but on a BA itinerary they would be. I think this one has further to go, not least if EU citizens find themselves unprotected.