Welp.
this was my first thought.
My second thought is that among the many reasons I'm not a fan of Trump is that his administration is so incompetent. Even if he wanted to play down the severity of the disease for whatever reason, they still should have been able to protect him from it. And I do understand that a President and administration (especially in the midst of a campaign) have to do a lot of essential work that makes it tougher to keep him safe but still. If they were just reasonably competent I really thing he would've avoided getting infected.
My third thought is that clearly there's a cluster of infections that occurred around the administration, and the debate was a very dangerous event when it comes to likelihood of transmission (close, indoors, lots of talking, no masks, together for a long time). So what are the chances Trump or somebody there infected Biden? Can you imagine if Biden also gets it and he is incapacitated? It's one thing if the guy losing the election dies, there's not really a crisis. But if the guy winning the election dies then even though it's clear how to proceed it would be pretty crazy. (The RNC would presumably nominate Pence to replace Trump and the DNC would have to choose somebody, probably Harris.)