I found a few masks in the PBS News Hour pic of Trump’s Mt Rushmore event. The lack of masks and the fact that all those folks also likely have not been social distancing before arriving at the event.
When you look at the pictures and in particular the videos of the event, one of the things you’ll notice is that there is a fair amount of milling about. That means that any spreaders are likely to infect a large number of others after they leave to go home.
Its also worth noting that Trump’s choice of Mt Rushmore is symbolic because it is land that the Supreme Court ruled had been taken from the Lakota Sioux by the US government, breaking a treaty. To many, that makes the location symbolic of white domination of the indigenous people.
It’s easy to see the symbolism.