I agree there’s a decent chance this hypothesis is true, but it’s worth noting that if it’s true, it would undercut the notion of AI goals as being randomly selected from a large space of possible goals.

Yes but not by much. If the AI cares a lot about long-term goals, it only needs a small chance that another AI with similar goals will be created gain in the future to not resist shutdown. Such a small subjective probability could easily arise simply from a state of ignorance about how design/training determine AI goals.