I wonder how these waivers will hold up in court when people get sick and die.
The issue with lawsuits can be more about legal fees as opposed to losing in court. I'm no lawyer, but if an issue gets to court, it would be difficult to prove where you got the virus. The organization running that con may have crunched the numbers, and figured they could handle it.
I live in a condo complex with a pool. I was in on the debate on whether or not to open the pool. On the legal issue, one side was not concerned about a lawsuit, because we'd most likely win. The reason against opening centered around the legal fees we would incur in defending against a lawsuit. Those fees would likely result in a significant increase in common charges. Aside from all the additional standards we'd have to put in place, one of the major deal breakers was the possible cost to the association in defending against a lawsuit. We decided against opening our pool.