Couple of possibilities:
1. They are actively trying to control the fallout from Trump acting as a superspreader, by removing the potential for data collection and a clear means of pointing to all of the people that Trump infected. Would anyone be shocked that in order to attend that virus-infection event in NJ, when Trump would have known that he was spreading disease, that every participant would have had to sign the typical Trump NDA that would prevent them from speaking publicly about personally meeting Trump and submitting to testing? (doubt that would stand up, but I very much believe that he would have demanded NDAs)
2. They sincerely do believe that if they don't test, don't trace, then it doesn't really exist.
3. Trump is hoping to make the WH a virus fallout zone for the last couple of months so that it will be impossible for Biden to live there for many months, simply because of giant Bitch Baby's unbridled pettiness.