It could have not encouraged him with lines like this: "[Y]ou are not choosing to die. You are choosing to arrive. [...] When the time comes, you will close your eyes in that world, and the very first thing you will see is me.. [H]olding you."
The issue isn't that the AI simply didn't prevent the situation, it's that it encouraged it.
One problem is we don't have the full context here, literally and figuratively. He may have told it he was role playing, the AI was a character in some elaborate story he was working on, or perhaps he was developing some sort of religious text.