One "rule" I've heard is that MOB wears pink and MOG blue. Seems ridiculous-I'd never have dreamed of telling anyone what they could wear at my wedding! If they wanted to ask bridesmaid colour because they wanted to be different, fine, but it's not up to me to dictate what adults wear. I even asked my bridesmaids what they thought and would never have wanted them in something they felt uncomfortable in.
OP, I know some people don't like the idea of red at weddings, but that's their issue. What matters is you feel comfortable. If you want, ask the bride/groom, as really no one else's opinion matters, but you'll probably find they just want you to feel happy and don't want to dictate choices.