Probably lots of reasons, all of them fucked.
The main reason is probably money. There’s no better way to turn billions of dollars of public funds into billions of dollars of private profits.
It also reassures neoliberals that for all his rhetoric about forgiving loans and improving healthcare access, he’s still willing to kill children if there’s money in it.
It’s also a chance to show off the unstoppable force of American arms against people who are considered completely expendable to America.
The only difference between the conservative Burundi government and the conservative American government is what they think they can get away.