The only confirmed deaths in the US so far from this virus happen to be where you live so I understand your local TV station telling its viewers to exercise an "abundance of caution".
And yes, you should be concerned about your dad in assisted living. I know first hand that senior citizen facilities, even under the best of conditions and cautionary steps taken when not dealing with things like Coronavirus, are major incubators of virus and sickness spreads.
I don't think it matters if an event is indoors or outdoors. The virus is more prone to be spread within large gatherings of human beings whether inside or out and likely affects older/seniors. Doesn't mean you'll die of course, especially if you are otherwise healthy, but you could be quite ill. And with OSH, we know the attendees skew older demo.