What information about the virus' nature and spread would cause you to believe it's too risky to continue holding workshops?
The CDC is currently warning that pandemic COVID-19 in the U.S. is likely and are currently moving their focus from prevention to mitigation. Specifically, the CDC has said that while they are “continuing to hope that we won't see [community] spread, ” the current goal is “that our measures give us extra time to prepare." Once spread within the US is confirmed, the CDC has noted that mitigation measures will likely include “social distancing, school closures, canceling mass gatherings, [...] telemedicine, teleschooling, [and] teleworking.” As CFAR workshops certainly seem like they fall into the “mass gatherings” category, the current guidance from the CDC seems to imply that they should be canceled once U.S. spread is confirmed and mitigation measures such as social distancing and school closures start to be announced.
I think the thing is that shutting down all social gatherings requires coordination to work. If there are no large groups, COVID-19 can't spread, dies, and you never have a pandemic. But if everyone else is meeting, and you don't, you'll just end up getting it from your wife, or a co-worker, or your neighbors or something. So you might as well hold the meeting if everyone else is going to be meeting.
What is unclear to me right now, and something I'm thinking about is whether countries and regions that don't yet have internal spread should be shutting everything down to protect themselves, and I think the answer might be roughly the same -- it might be worth it if everyone did it, but if the virus is going to survive somewhere no matter what you do, you might as well wait to shut down social events for your city and region until you actually need to, since you really, really don't want to be in lock down longer than you absolutely need to.
COVID-19 provides a very interesting case for applied rationality. Most people don't reason about it in a way that leads to effective action. It's a good topic for teachable moments.
In a case where there's higher risk from COVID-19 CFAR workshops could start by teaching participants proper hand-washing technique and drill best practice to lower infections into all participants.
Summary: I see very little danger for now, particularly in this group. If basic hygiene stops working I'll be more worried.
I weep for the group of aspiring rationalists who can't even be bothered to wash their damn hands. By all accounts, that's the easiest way to severely limit the spread of COVID-19. Fatality seems to go up with the age of the patient, and if the 2020 SSC survey is any indication, the average age of this group is in the low 30s. Nearly all of the confirmed cases of COVID-19 have been in China (77.6k chinese cases / 80.2k global cases = 97%) [Johns Hopkins data and visualizations], so maybe we shouldn't have CFAR workshops there.
(edited for formatting and clarity)