I agree. I need more pics. The one shown is NOT a bull pup. Looks like a 'Finetooth' (Carcharhinus isodon), which are often sold in the pet trade as a "mini bull shark". Also, I've studied bull pups that were so young that the umbilical was still partially there. 33" (article says 2' 9") is not a year old bull pup (as the article says), it's a runt from that year. That size matches a year old Finetooth.
Yes, bulls go up the Mississippi all the time. Dams stop them from getting too far. There are FW isolated bull populations found through out the world.
I'll see if I can dig out bull pup pics to show the tooth and rostrum shape differences between a real bull and the pic in the article.