The thing about the arms-trade with America is that the USA provides tax-payers money to that nation, which then used to buy the over-priced American military equipment from private companies in the USA. e.g. it's a money-laundering scheme for politicians who are getting campaign money from those same manufacturers but they can do it under the guise of "aid". This is one of the main reasons they'd be pissed at Duterte.
Lockheed Martin, who make the F35 fighter, are in the top 10 campaign donors in the USA, for example. e.g. politicians directly benefit from approving these cash transfers and arms deals. So when Duterte says to keep your $200 million and that he doesn't wish to buy $200 million worth of American fighter jets, politicians in America are losing out on their bank balance.
Personally, I find the thing about US politicians caring about a few thousand dead drug users ... kinda suspect, considering they often flat out refuse to acknowledge a lot of abuses committed by friendly governments, e.g. Uribe's Colombia, which was called a "Model Democracy" by Bush, despite widespread political killings against government opponents, in favor of wall-to-wall negative reporting of a government that isn't even on record for the government killing anyone, e.g. Chavez's Venezuela.
Sure, clearly some politicians in America do actually care, but given how hard it is to get most of them to care about various atrocities, I get skeptical when all of them suddenly discover human rights in relation to some country that's challenging US hegemony.