Another reference to city responsibility

Searching for conservation easement, I found this on FindLaw:
http://realestate.findlaw.com/easements/conservation-easements.html

Property Entry and Inspection
The organization that holds the easement has the right to enter and inspect the property and is legally obligated to assure that the property is in compliance with the terms of the easement.

The city is saying they can cancel the agreement.  In the terms of the agreement, the city was given the unilateral authority through their written consent to allow the prohibited activities.  But what about the "intent" of the agreement - wouldn't allowing building or rescinding the agreement go against the conservation intent that this was set up in perpetuity?