The US especially have a reputation for sending ignorant people to be ambassadors as political favours.

Just checking, I came across an article published a couple of days ago about Dr. Anjani Sinha, President Trump’s pick for U.S. ambassador to Singapore, being “grilled” (quoting article) in the senate. So you might have been reading about a different senator (and I don’t mean that to say “haha wrong” but rather “this happens a lot”)