Sure, but a lot of the hypothetical nanotech disasters are things that require nanotech devices that are themselves very small (e.g. the grey goo scenarios). If one requires a macroscopic object to keep a stable vacuum then the set of threats goes down by a lot. Obviously a lot of them are still possibly present (such as the possibility that almost anyone will be able to refine uranium), but many of them don't, and many of the obvious scenarios connected to AI would then look less likely.