The point of a pressure cooker is to allow higher temperatures than 100°C, which cooks things faster. But anything higher than 60°C should kill almost all bacteria (possible exception: rice bacterial spores) if you cook it long enough. Have you done a side-by-side comparison of food cooked in a pressure cooker vs cooked at normal pressure?
Killing spores is a lot harder. They can sit around in harsh conditions for a few hundred years until the conditions are right to germinate. And cooked foods devoid of other life (competition!) is a perfect situation.
There’s a lot floating through the air, not just what comes on rice.
For immediate consumption, it’s not usually necessary to kill them, but for storage it can be.
