Deformity caused by tb in live bearers is pretty common i think. Could just be an old geezer too like you said, lolBad genetics, infection (TB), old age. There are many reasons why fish get bent spines like that. Its quite common.
Yes, I read that about tb before too when I was doing some research on ram cichlidsIf its a young fish id opt for genetics, and old fish just old age, in between infection. If you think its infection then i would isolate it so it doesn't spread. If you think its genetics or old age and it doesn't appear to be suffering i would say just leave it be. If its suffering....
TB in fish can transmit to humans i read recently.