There is also a critical mass element. A gathering of 10s of thousands from all across the globe is a lot different than hundreds from the local community. Cancelling things like GDC, SXSW, Emerald Comic Con, etc all make a lot of sense. They gather a large number of people from a large region. I wouldn't cancel a local D&D con that only pulls in the local community unless there was a clear directive to do so. A former coworker has a cruise scheduled in a few weeks down to Mexico. I personally wouldn't go. Again, too many people from too far of a region.
But, if work needed me to go to SF to meet with a vendor I'd probably do like Jake and drive over. Work still needs to get done. So I'll do it in a way that reduces my exposure and potential spread.