I would have been extremely irritated by this situation. A few years ago, before one of my children had surgery, we took great pains to make sure she was not exposed to illness. If she got a cold, congestion, or fever her surgery would have had to be rescheduled for a few weeks alter. We would have had to repeat blood work, physical exams, etc. It was stressful enough that she needed surgery, without having to go through all that.
If someone told us not to come to an event if we were not healthy, I would assume I could safely bring my daughter without risk of exposing her to something. I mean, why would someone make such a request, yet think it was OK to expose other people to illness? It would never occur to me that someone could be so rude and thoughtless.
Let me amend what I said: if it happened now, I'd be irritated. If it had happened then, I would have been furious.