Theory of the boltsman brain is that intelligent beings are not brains floating out in empty space. David Wallace says he doesn't want to give zero credence to any logically consistent possibility, because if you do then literally no future information can make you believe it. So his current attitude is just say no to bolts and brain cosmologies. And if evidence comes in that it's a better fit than what i think, then i'll change all up date accordingly. But it won't be a formal basi in up dating. It'll be fuzziness becoming a little bit clearer.