We routinely create aliases on DB2 z/OS that reference tables in a remotely catalogged DB2 LUW database:

create alias MYSCHEMA.MY_TAB LE for REMOTEDB.MYSCHE MA.MY_TABLE;

When we create an ALIAS on Z/OS for LUW table SYSIBM.SYSCOLUM NS and try to SELECT from it, we get this error:

DSNT408I SQLCODE = -204, SQLSTATE = 42704, SYNTAX ERROR OR ACCESS RULE VIOLATION FROM DB2 UDB FOR AIX,LINUX,HP-UX,SUN AND WINDOWS...