LOL. Probably you're right but it was hard to tell because those tits are so huge that they hide any signs of a fat gut.

I interpret "thin" as a woman who doesn't have so much fat that the normal female shape is deformed and at the other extreme not so lacking in fat that bones and veins are bulging through the skin.
Most busty women seem to be "big boned" or of a chunkier build but would still be considered thin by the majority of people.