BA would prefer culturally aware pilots. That question probably exists to check you're not some UKIP voting, Daily Mail letter writer. But it seems some of you are ;-)
Think about it. You're getting upset about a politically correct question? Don't you get it? You'll be sharing a cockpit with a diverse ethnic/sexuality/gender spread in BA. If you get all het up at the ambiguity it'll just prove you're another one of those veiled intolerant-types that quite frankly, we have enough of in BA already.