To him, government efficiency means that the government is out of the way and no longer interfering with his efficiency. Might as well just do away with it entirely.
Companies are not democracies, Musk says "get rid of the supercharger team" and no one gets a vote, they just get rid of them. We should all be worried about what goals he efficiently wants to achieve, if you or I were in the way, would he care.
The danger is in the unchecked nature of this power, even if someone likes Elon Musk and thinks he's a brilliant genius, what gives him the right to supplant the will of the people with his own.
Elon has shown time and again that he will prioritize what HE wants, and if that means some people don't have jobs, well that's just fine. If that means that people should have to sleep on the factory floor and wake up and make cars he can profit off of and then back to sleep on the factory floor, that's also just fine. If that means that USAID doesn't feed the hungry, that's also just fine.
And maybe to anyone reading this that's happy with what he's done, you are just fine with it too. But what happens when he decides something you do care about is alright to destroy too to meet his goals, he's just fine with it. What do you do then? How confident are you that your goals and his will stay aligned, forever, that the ax of "efficiency" won't come for you and yours someday. And if that day comes, what will you say to the people that tell you "he's a brilliant genius and he's fine with it so so am I"
For some people, that seems to be fine. They work at SpaceX and Tesla and his other companies. For many of us, life is the journey and the quality of it matters, not the Martian destination, and he can fuck right off.
Also trust is earned. Do I have to remind you of the hundreds or thousands of lies, many of them very recent, of these people?
Why do you believe this? Because Elon Musk said so? Elon says a lot of outright false shit. So does Trump.