Bro, Kaido and Harald look more similar than Rocks and Buggy do. Also, that tongue pose is nothing unique. Other characters do it too
Buggy and Rocks do, Oda gave them the same pose (and It's not the tongue alone, It's the hand too: the two pics are a literal mirror). Before that, there was THE OTHER "pose" too, and people already made 2+2 on Buggy.
Then, as said, you have Shanks, Buggy's spiritual brother, who turned out to be the secret son of a would be Gorosei, aka with a top world secret lineage.
Etc.
