afaik because in islam circumstances are all important. if muslims are not driven from their homes, or fought for their religion then the advice is to deal with the situation in an amicable manner.
with regards to kashmir and religion, much depends on pakistans actual intention. nifaz-e-shariah or nifaz-e-her majesties law circ1940
having said that, pakistan already has a form of shariah and thus has a good case under all religious and political laws for kashmir, but im no scholar