The chances are he didn't want you drinking because he was gagging for one himself and his missus doesn't know he likes a slurp. I would have invited him to move himself, as it's his problem not yours.
As for Ramadhan, I don't observe it, because I'm not pigging out all night, so if there's food on the plane I will eat it if I so choose. A devout Muslim will consider himself closer to Allah if he can fast in the face of temptation.
And more to the point, you are exempt from fasting if you are travelling, or you are sick.