I'd argue that we are (and not just for mosquito nets), we just rationalize it away and forget it. Distance helps a lot, in that sense. But this guy is likely to meet or talk to people who were directly affected by his decision, basically every day for the rest of his life.

What if your job is to do something to save lives?

To take your analogy to its logical conclusion, you're also saying a firefighter isn't responsible for a building burning to the ground, even when he's standing in front of the building with a hose in his hand.