His point was that the Hulk can be beaten. If someone was able to take down Thor one on one (who is just as or more powerful than Hulk) then that's someone to pay attention to. Same with Xorn and Zorn. Zorn was able to actually separate the two before Hulk even got close to him.
Also, as to why everyone really wants to see the First Knife guy-Bobba Fett syndrome.