Actually, this is the most misleading thing I’ve ever seen. People assume that muscular characters are generally brutish with low IQ, but Kaidou is by far the most intelligent character we have. He’s portrayed as calculating, smart, running an empire for decades, would have Vegapunk working for him, supplied weapons to the world, maintained alliances, and reigned for decades.
There isn’t a single argument you could pull from the manga to say: “Kaidou is dumb, look at this.”