Musk is ambitious. He wants to do Big Things. He feels he is a better kind of human being, and wants to make the world in his image. Literally, in the case of Mars. For the US, he wants to free it up to do the kinds of things that Great Men do, which mostly means eliminating waste from the government (defined as anything that helps minorities, protects the environment, or anything else that doesn't have a direct benefit to him and the other ubermenschen).
The problem of radiation on Mars is something for his underlings to work out. And he's probably right: they'll find an answer.
As for the programs he's eliminating... they can't come back while he is in charge. Certainly not in the next two years, and he's convinced he's cracked the code for ensuring that subsequent elections will also go his way. And he might be right about that, too.