Egypt has tried very hard to comply in every way with the peace treaty. Israel's treatment of the Gazans has made that policy a huge burden for Egypt. Now, for a while, Egypt has no choice but act in it's interest instead of as a thug for Israel. When the smoke settles, they will close the border.
U.S. to defend Syrian rebels with airpower, including from Assad (Reuters)
from the article: Egypt opens Gaza border following IDF raid on aid flotilla