That seems to ignore the fact that two 9/11 hijackers had cutaneous anthrax. And that they rented an apartment from the boss of the man who died of anthrax in Florida.
2. The hijackers moved around a lot .
I think it more likely al-Hazawi had a spider bite,or an infection from sandfly bites (quite common in the Middle East).
As to Atta's reddened hands,I'd be more likely to think he had been making up explosives.(There is some indication the hijackers on all 3 planes carried explosives aboard.)