Thousands March in Egyptian Capital Calling for President’s Ouster

[Magda Hassan]

I expect it is mostly to do with control of the Suez.

There is also the issue that there could not be any UN observation force to ensure the treaty due to the veto of the USSR (then) so Israel, Egypt and the US made their own security arrangements outside of the UN.

http://en.wikipedia.org/wiki/Egypt%E2%80...ace_Treaty
and
http://www.mfa.gov.il/MFA/Peace%20Proces...e%20Treaty
In particular this
Article IV

1. 
   
2. In order to provide maximum security for both Parties on the basis of reciprocity, agreed security arrangements will be established including limited force zones in Egyptian and Israeli territory, and United Nations forces and observers, described in detail as to nature and timing in Annex I, and other security arrangements the Parties may agree upon.
   
3. The Parties agree to the stationing of United Nations personnel in areas described in Annex I. The Parties agree not to request withdrawal of the United Nations personnel and that these personnel will not be removed unless such removal is approved by the Security Council of the United Nations, with the affirmative vote of the five Permanent Members, unless the Parties otherwise agree.
   
4. A Joint Commission will be established to facilitate the implementation of the Treaty, as provided for in Annex I.
   
5. The security arrangements provided for in paragraphs 1 and 2 of this Article may at the request of either party be reviewed and amended by mutual agreement of the Parties.