Very simply, Egypt recognizes that Israel is the legal "occupying power" of the Gaza strip. (According to the UN and most nations, except Israel, Israel's occupation continues since it exercises "effective control" over Gaza.) Egypt follows the Israeli demands. Even when it "violates" whatever stricture Israel imposes, it is done for Humanitarian needs where there is some legal cover for such an action.
17-year-old Palestinian killed by IDF on Friday laid to rest near Ramallah (Haaretz)
from the article: In response to Bernard-Henri Levy