The kind of national agencies that have the capacity to make the hacker "have an accident" develop their own systems in-house. As far as I am aware the market for products like FINFISHER is ordinary LEO and crappy regimes in the middle-east and Asia that don't have the capacity to black-bag a foreign national.
Maybe I'm missing something in the article, or disclosed elsewhere, but we don't know who s/he is. If the CIA put Thorium in their sushi, we'd have no way to connect the dots.
Edit: I think they'd be far more likely to prosecute them than assassinate them though.