I would be willing to bet a substantial amount that Castro offered that money for the sole purpose of embarrassing Bush, knowing that we'd turn it down
Castro is a lot of things, but stupid isn't one of them. It's a no-lose proposition on his part. Bush either accepts it and pisses off half of South Florida, or rejects it and looks like an ingrate. Either way, ol'
El Jefe comes up smelling like a rose.