I've been thinking over this whole USAID issue. Here's how I see it:
Musk, Trump, and their allies are basically using one argument to support their moves here: that USAID does bad things. That's pretty much it. So yeah, I'm sure you can point out times when USAID funding or programs were tied up in some bad s***. Helping the CIA overthrow a Latin American government or something. I'm skeptical of some of these claims, but I'll acknowledge that some of it probably happened.
The problem is that there also seems to be some good stuff that USAID does (curing diseases, feeding hungry children, etc.) and Musk/Trump have offered no accounting for how those things will continue or be improved. You can't shut down a whole department and not have people asking questions about the programs that are good! Especially when many of those initiatives were in fact passed into law by Congress and should not be thwarted by the President (absent a new vote in Congress). That is really the issue here, not whether or not USAID is a perfectly virtuous organization. That latter argument is a red herring and just an attempt to muddy the waters.
This also reminds me a lot of Trump and the Republican effort to "Repeal and replace Obamacare." For a while, all they had to do was talk about why Obamacare was bad, the inefficiencies in the system, how some individuals and small businesses saw their premiums rise, how the website didn't work, etc. Some truth to all of that! The problem is that when it came time to repeal there was no replacement on offer, so rather than fixing the problems with the system it was just going to be taking people's health coverage away. I see a lot of these Musk efforts crashing on those shores eventually. He has not articulated a constructive vision for how to rebuild at all. I hope to see something like that soon, but I am not holding my breath.