Yes, a flag value of 1 means that the parameter has been removed, and a flag value of 2 means that is has just been hidden. You should not find any NULLs.

Do you know what the column values in X$KSPPO.KSPPOFLG mean? The column contains either NULL, 1 or 2 and I found a reference which hints that it could be some sort of indicator as to whether or not the parameter is desupported or deprecated.