Using the IF Operator in Scope Assignments

UDM scope assignments are incredible useful because they let you write to the cube space, such as to implement custom aggregation, allocations, currency conversion, data calculations, and so on. Unfortunately, scope assignments have limitations. One of them is that more complicated scope expressions result in "an arbitrary shape of the sets is not allowed in the current context" error. Recently, I tried to use a scope assignment to zero out a cube subspace that the end user shouldn't see and cannot be protected via dimension data security. I tried the following scope assignment (translated to Adventure Works):