I'm going to say brainstorming, as Platt isn't leaving any time soon and Galvin is kind of busy on the other coast these days.
Having said that: Galvin certainly has a lovely voice that would suit the score well. But there is a world-weariness to his personality (both IRL and onstage/onscreen) that feels 100% antithetical to the character.
"You travel alone because other people are only there to remind you how much that hook hurts that we all bit down on. Wait for that one day we can bite free and get back out there in space where we belong, sail back over water, over skies, into space, the hook finally out of our mouths and we wander back out there in space spawning to other planets never to return hurrah to earth and we'll look back and can't even see these lives here anymore. Only the taste of blood to remind us we ever existed. The earth is small. We're gone. We're dead. We're safe."
-John Guare, Landscape of the Body