Not only did they want more people crowded together in Tulsa, but they planned an overflow area, which at least was outdoors, but also would have had more people jammed together.
It really is bewildering that they didn't choose
1) an outdoor arena where they could at least plausibly claim the chance of transmission was low/lessened;
2) a bigger city or smaller arena where they could get the number of attendees/optics they wanted. Of course in viral terms, that would have been a disaster, but in short-term political terms a half empty arena was a hit too;
3) a more contested state where folks might be more motivated to risk their health and attend.
Just seems odd how badly done everything Trump is involved with. They are going to have to do a huge hatchet job on Biden to have any chance. Can they get their act together to pull off negative hit jobs on Biden?