Chanah, as I wrote in my title, I have no reason to doubt this story, unfortunately war often brings up the worst in mankind. I was just saying that from an Egypt point of view there will be a certain suspicion with regard to the timing of the story. And with regard to a difference between prisoner of war and troops in retreat: of course there is one, but there is also an (inofficial) honour codex in the army, which says that you shouldn't attack (defenseless) troops in retreat. One of the worst examples were unfortunately the Americans during the first Gulf war, when they killed thousands of Iraqi soldiers who were retreating from Kuwait.
Russia: U.S. plan to provide air cover for Syrian rebels undermines Damascus fight on ISIS (Reuters)
from the article: TV documentary: Egyptians killed captured IDF troops in 1973 war