Exactly. If you have determinism in the sense of a function from AI action to result world, you can directly compute some measure of the difference between worlds X and X', where X is the result of AI inaction, and X' is the result of some candidate AI action.

As nerzhin points out, you can run into similar problems even in deterministic universes, including life, if the AI doesn't have perfect knowledge about the initial configuration or laws of the universe, or if the AI cares about differences between configurations that are so far into the future they are beyond the AI's ability to calculate. In this case, the universe might be deterministic, but the AI must reason in probabilities.