iam role trust policy behavior

Hi

aws docs mentioned that iam role trust policy should be treated as a resource based policy but in fact it doesn't .

regularly iam user could get a permission from his identity policy (resource level permission) lets say s3:getobject then he will be allowed to do that action unless an explicit deny exist regardless of the default implicit deny on bucket policy .

so in case of iam role trust policy , lets say : role "A" trust user "B" in the same account if another user "C" in the same account had "sts:assumerole" permission in his identity based policy as a resource level permission then he should be able to assume the role even if user "c" is not in the trust policy which does not happen .

the current behavior is more like an explicit deny for any principal not specified in the trust policy .

it is not the default/documented behavior of the resource based policy which should be an implicit deny .

any thoughts ?

thanks