The US government can still get at that data, because Amazon is still an American company. It doesn’t matter where the data actually lives.
Unrelated, I think this also happens the other way around.
Sounds about right ...
Every time they make use of a zero day or a backdoor they run the risk of it being discovered. The harder it is to get a new one, the more they will think twice about using it for mass and low stakes surveillance. A non-US company will be less inclined/forced to cooperate with them, making it harder for them to siphon data out, hence lowering probability.
No one is 100% safe, agreed though. Probabilities and threat models is all we got.