Even if you subscribe to the notion that US government should not be paying for this, you can phase it out with enough notice for others to step in and take over the funding. The flippant, "tech disruptor" method of abruptly ending an organization that has for decades been funding critical public health initiatives in countries where they would otherwise not happen... That is the truly infuriating part.
In the grander scheme of things, the US voters do indeed have the right to vote for not providing foreign aid. Which is sad of course, but is a valid political position.