Hi Sri Ram,
Since this is a .unx and CR4Ent environment, probably there is a way out from the .unx end. Please post this to the Semantic space as well.
You would need to create a security table to hold the user_name,user_id and the campus_id at the database end and include this table in the universe schema.This table will 'join' with the 'dimension' table on user_id. A 'where' clause restriction like @variable('BOUSER')=user_name will have to be applied on the dimension table in order to fetch the necessary records per the user.
The names stored in the security table have to match exactly with the list of BO users, only then the @variable('BOUSER')={security_table}.{user_name} will get the required results.
Further, you could also create a cascading LOV in the universe and restrict it based on the same logic,so as to enable the required prompting for a 'district' user.
-Prathamesh