No, this won't necessarily save you if you see some impossible scenario like a boat cruising down the highway toward you, but it does mean that the list of conditions the model can't respond to reasonably will rapidly trend toward "fewer than most human drivers", in the ideal case.
This will, invariably, have some unfortunate bumps when people discover real-world conditions that, for whatever reason, the model doesn't remotely have responses for (I wonder if they've trained it on e.g. an enormous wall of water, or tornadoes?), but that's why you don't claim it's an always-on self-driving system (e.g. you have to be ready to take over at any point), and arguably the error rate is still going to be lower than most humans to start with.