That's the worrisome bit. Trumpists whine that people were protesting during a pandemic, and there is a concern about that, but many of the people on the street were wearing masks and they were outdoors. It won't be surprising if many at Trump rallies refuse to wear masks out of spite, and they'll be close to each other at an indoor venue.
The sad thing is that you can almost see the news headlines a few weeks after each rally... "2,000 people at the latest Trump rally contracted COVID-19, 500 went to hospital, and 100 died."