I would pose the question in the TWRA Questions Forum. But here is my best (semi-educated) guess. Chumming is perfectly legal provided what you're using to chum with is legally caught.
Just like using game fish for catfish bait. If the fish is legally caught (on rod & reel), and of legal size, I can cut that fish up and use it for catfish bait. I do it all the time with bluegill.
But if I catch bluegill in a cast net, they must be thrown back in the lake. It would be illegal to use them for bait since they were caught illegally.
So if I catch a skipjack on a rod & reel it's perfectly legal for me to cut it up and use it for catfish bait. So if I can cut it into big pieces and put it on a hook, why shouldn't I be able to cut it into 100 tiny pieces and drop them back in the lake without a hook?
I used to catfish with a gentleman who would fill a plastic mesh sack with dry dog food. He would tie it to his anchor rope when he dropped anchor to fish, theory being the dry dog food would dissolve, drift downstream and attract catfish. We caught fish, but I'm not convinced we wouldn't have caught them anyway.