So, in answer to my question, there is nothing she could do.
Quite right. There was nothing she could have done that conservatives wouldn't have attacked with equal fervor.
She was faced with the questions of (1) do I reveal my pneumonia? and (2) do I attend the 9/11 ceremony?
Let's put ourselves in her place.
4 alternatives face her:
If she doesn't reveal her pneumonia, and doesn't decide to rest, they'll attack her for risking her future health.
If she doesn't reveal her pneumonia, and does decide to rest and skip the ceremony, she looks like she's thumbing her nose at the 9/11 victims.
If she reveals her pneumonia, and doesn't decide to rest but rather to attend the ceremony, they'll attack her for being contagious.
If she reveals her pneumonia and skips the ceremony, they'll say she was lying and was disrespecting the 9/11 victims.
That's their game. They criticize no matter what with equal fervor.
A decision is only particularly bad if there was something she could have done better.