Feed them rice cereal next time they come over. That stuff tastes gross!! I never really bought into the bland food theory. We did BLW and by the time he was 1, DS was eating what we eat.
Personally I hate bananas (always have even as a baby!) but they are good for you so just ignore the negative nellies and delete their comments from your photo.
Besides, lots of veg is sweet! Sweet potatoe, pumpkin, and even carrots are sweet. So their theory is wrong and is nothing but an old wives tale. Don't let their outdated info get to you.