A lot of people worry about falling sick while in another country. It's normal.
Although you got to take precautions, what you need to do is also to train your body to take a bit of "dirty" food. People who lives in very clean environment tends to have weak stomach and this becomes a problem when traveling to other countries. I can understand that sportsmen like AUS120 not taking any chance and decided to prepare his own meals after all he was there for training.
I always asked for ice in my drinks while I was in Dahab. My kids ate the ice too and they were ok. (By the way, ice is a precious item in that hot country, you may not get it sometimes).
Egypt's population is growing so how unclean can their food be?
Just look at what Bear Grylls ate for survival! Yes, I believe our human body is quite adaptable and quite capable of self-healing, sometimes (: