What I did to make my characters that wouldn't talk a lot talk to other people was put them in humorous situations. Because people will usually tag into something funny than something serious (much to my dismay when a character is having an existential crisis). And usually if it's an unusual enough situation, even the most quiet of characters has to react to it. Or under-react to it.

Also tagging in on people that can carry the thread helps. There's not been a lot of opportunities for subjects that Boone would be interested in to come up.