Here are the quotes I could find:
<small>Chapter: 120, P11.1-2
Context: Goku revealed that he defeated Taopaipai. Tenshinhan did not believe it.
Jackie Chun: “Did you really…take down Taopaipai…?â€
Goku: “Huh? You too, gramps? I did so! It wasn’t easy, though…him being so strong and all.â€
Jackie Chun: “Taopaipai…said to be the world’s Number One assassin…and this lad…he…he…â€
Chapter: 122, P12.3-6
Context: after Goku defeats Panput
Tenshinhan: “That wasn’t one blow. While brushing off his opponent’s fast punch with his right hand, with his left he showered him with…3 rapid-fire elbow blows…That brat, he’s no ordinary person.â€
Tsuru-sennin: “I see…maybe he really did defeat Tao Pai Pai…â€
Tenshinhan: “This tournament is finally getting interesting…â€</small>
Nothing about Taopaipai being "invincible", though.