How long will it actually take for a self-sustaining colony in LEO to be plausible? We have the ISS and Biosphere 2, and have for quite some time. Zero G poses some problems, but certainly not insurmountable ones. It looks like we have at least a few hundred years of advance notice, which would likely be enough time to set up an orbital colony even with only current technology.

Besides, it looks like past a couple hundred miles, the eruption would be survivable without any special, though agriculture would be negatively impacted.