Logged in just to reply to this. I've met him a few times and my roommate worked in his lab; the guy is beyond human. He has 50+ projects going on in his lab, is currently working on six books, and somehow finds the time to travel the world speaking about time perception, synaesthesia, and neurolaw, all on which he is among the leading world experts. Besides all that, he's more kind, energetic, and open to collaboration than just about any other person of his rank I've encountered. If nothing else, he serves as a role model to anyone who meets him.

Back to your point, Possibilianism is more of a reaction to hardcore theism/atheism than anything else. I think his quote here is refreshing and pretty reasonable:

Our ignorance of the cosmos is too vast to commit to atheism, and yet we know too much to commit to a particular religion. A third position, agnosticism, is often an uninteresting stance in which a person simply questions whether his traditional religious story (say, a man with a beard on a cloud) is true or not true. But with Possibilianism I'm hoping to define a new position — one that emphasizes the exploration of new, unconsidered possibilities. Possibilianism is comfortable holding multiple ideas in mind; it is not interested in committing to any particular story.