That completely depends on the nature of the failure. This speech was written for a broad range of possible causes. Capsule explodes on takeoff from the moon?

That completely depends on the nature of the failure. This speech was written for a broad range of possible causes. Capsule explodes on takeoff from the moon? No last words. Discover that nobody remembered to refill the rocket fuel? Sure, they have quite a few days of life support​. Though I expect that, like the story of the doomed cosmonaut Vladimir Komarov (who was allowed to say goodbye to his wife privately as his capsule burned up as it careened, parachuteless, through the atmosphere) their last words might not be something that NASA or Nixon would want to broadcast.