Because everyone expected Egypt to crackdown as they had in the past as is occur in Bahrain. So the question should be why did Israel not foresee Egypt not cracking down. Which means that the intelligence failure is in relation to the US not Egypt at all. As it was the US position that prevented a crackdown.
Obama to meet with Jordan's King Abdullah in White House later this month (Reuters)
from the article: Why was Israel clueless about Cairo?