“Edwin Lyman, director of Nuclear Power Safety at the Union of Concerned Scientists, a nonprofit, said his organization is concerned the parameters of the design and timeline make the most likely reactors those that use highly enriched uranium, which can be made into weapons. Nations have generally been attempting to reduce the amount of enriched uranium being produced for that reason“

The enriched uranium for a handful of deep space reactors has pretty much a zero chance of being used in weaponry, especially once it’s been launched.

This seems like a trivial proliferation issue when you realize the US still has thousands of nuclear bombs and continues to make new nuclear weapons.