do the Girls namun, bawang putih and bawang merah, which mean 'garlic' and 'shallow' imply something?

garlic or bawang putih are spices that's used for flavoring and in herbal medicine 
red onion (bc swallow means menelan) or bawang merah is often used for food decorating.

in the story bawang putih is very nice but bawang merah isn't
so based on the explanation AND the story
1. (in herbal medicine) they make you healthy and they won't harm you (unless you ate too much)
2. (often used for food decorating) they are prettier from the outside, but not the inside

in the story bawang putih is very nice but bawang merah isn't
so based on the explanation AND the story
 (in herbal medicine) they make you healthy and they won't harm you (unless you ate too much)

I hope this helps