Using Linq on a Client Object model result from sharepoint

I am trying to use LINQ on a result i get from Client Object Model.

var rolesAssignments = context.Web.RoleAssignments;
context.Load(rolesAssignments, 
    roles => roles.IncludeWithDefaultProperties(role => role.Member,
    role => role.RoleDefinitionBindings));
context.ExecuteQuery();
var hasAdmin = rolesAssignments.Select(x => x.RoleDefinitionBindings.Cast<RoleDefinition>().Select(y => y.RoleTypeKind == RoleType.Administrator)).Any();

I get:

{System.NotSupportedException: Invalid usage of query execution. The query should be executed by using ExecuteQuery method on the client context object.

However, when i rewrite this to use a nested foreach loop, it works fine.

From what i can see from my linq query, im not using any properties thats not loaded.