The comparison on ' ' into "case when" conditions on union sighting with constants in the array list

SQL-Example:

create table test_rf (MEKZ NCHAR(2), id int);

-- Datarecord with 1 space
insert into test_rf values (N' ', 1);

-- Create View
create or replace view test_rf1 as
       select N' ' as MEKZ , id, 'cons'  as typ from test_rf
union all
       select MEKZ, id, 'data' as typ from test_rf  


select id, case when MEKZ = N' ' then 'EMTPY' else 'NOTEMPTY' end as MEKZ_STATE, typ from test_rf1

Result:
ID MEKZ_STATE TYP
1  EMTPY      cons
1  NOEMPTY    data



Expects war is have here all data records in the field the MEKZ condition cave EMPTY value