I got ya, man. Had to break it down to something physical: only those who are Houstonians are Texans. That statement doesn’t make any sense because you don’t have to be a Houstonian to be a Texan. However, “only those who are Texans are Houstonians” does make sense. You have to be from Texas to be from Houston.
Thanks for clearing it up for me, man. I know I shouldn’t really care about whether the statement makes sense, but I guess I could only make sense of the logic by hearing something that I can visualize with the same structure.
For sure helped, and thanks again,