Nice catch – I'd originally intended to have a slightly more complex interaction between nanobots and space colonization tech, but wound up having to cut that in order to make the FermiJam deadline. For the time being, I'll probably just make the space colonization tech zero out the probability of the gray goo event (just like it currently does for the asteroid and volcano ones).

For what it's worth, the same can happen with all-out nuclear war:

The Gogko have begun to establish permanent colonies on worlds other than Kog‑gop. Although still largely unable to travel outside of the Kilgko system, the distribution of Gogko civilization across multiple worlds greatly reduces the risk that they will collapse due to any crisis of merely planetary scale.

In 24628, an early warning system employed by one of the major Gogko superpowers detected an incoming nuclear attack. Whether the alert was a false alarm remains unclear, but the resulting nuclear counterattack and ensuing full-scale nuclear war has plunged Kog‑gop into a state of nuclear winter from which it is unlikely that Gogko civilization will ever recover.

For what it's worth, the same can happen with all-out nuclear war:

Nuclear war now seem to be prevented when a world government is established.
Fixed in: cb84e6c#diff-9a3b63829bb24007e1aafff213bca5dfca8c46296f4917edc3b5d5475ea13057