Yes, I agree that you should also not dismiss the brain when making decisions. This is widely assumed to be the desired, appropriate behavior. (Whereas dismissing your gut is widely regarded as the right thing to do, which is actually a wrong thing to do and is an avoidable bad decision.)

However, I think you underestimate the brain thinking that the anti-vaxxers are making—-believe me, they have done hardheaded rationalization of their beliefs.

Egg-headed decisions come from bad brain thinking, not from trusting your gut.