Should I use raw turmeric that turned rubbery?
This is very common, I store my turmeric and galangal in the freezer and they always come out a bit floppy. This isn't a problem if you plan to grind, puree or grate the turmeric as you are breaking down its structure anyway (grating may take a bit more effort than harder turmeric but it's very doable). 

If your recipe requires shaping the turmeric in some way, like cutting fine strips, you may have some trouble as it won't cooperate with you.