The issue is that any competent law firm will pull up articles and comments by officials stating that warm weather will dampen or hinder COVID-19 spread. They would only need to pull up a video of Trump stating as much and make a case that it's "reasonable" to believe the president.

And even more serious sources basically say: "we don't know at this time", which is not enough to make these actions criminal (as per current laws, per my limited unprofessional understanding).