I don't doubt Burr told him to sell.
I am not sure the reason he did was that he had material, nonpublic information. He may have been given an economic opinion and decided to sell. I don't think that would be illegal.
It really depends what sort of information caused Burr's decision. If he was given access to unreleased government data and made his decision based on that, that would be a problem.
If it's investigated, I think they'll find out the probable cause very quickly.
But I don't think the risk of covid was unknown at that stage.