Yes, you are being too cynical. There is no way that anyone who chose to work at 18F - a place that exists to make government actually more efficient, that has a reputation for quality and execution, and that doesn't pay nearly as well as the private sector - is at all okay with Musk's slash-and-burn version of "efficiency". This kind of message exists to point out the difference: if you actually care about efficiency and good governance, you wouldn't possibly dream of firing these people. Hanlon's razor can't even explain it; even if you're an absolute moron you wouldn't do it. The only possible explanation is actual malice.