This reminds me a bit of Solomonoff induction.
The prior stays universal (dominant) even if you switch an initial finite segment, corresponding to the switching of the base universal Turing machine used to encode the Kolmogorov complexity.
Here naturality to me seems connected to the Kolmogorov complexity, as induced on the agent evaluating it by its environment. But what's important is not the environment, but the agent. If an agent had an internal lamp that switched color every now and then, for that agent grue/bleen would be the most natural (i.e. least complex) choices.