It seems odd for me to refer to Captain Kuro as dumb when he's easily one of the most intelligent characters in the show but his decision making had more holes than Swiss Cheese.

To be fair, I doubt he'd planned for Luffy to show up, in order to evade capture, he used Jango to hypnotise Axe Hand Morgan, the only survivor of Kuro's massacre into thinking Morgan captured him but placed a fake instead, pretended to be a victim of pirates to gain trust into Kaya's estate as her butler, the fact that he already looked and sounded the part helped, he also gambled on the town eventually ignoring Usopp's cry wolf phase and even stopped a mutiny when he was called out by his crew for how long the plan was taking, but he made the fatal mistake of being too impatient when attacking Merry, when if he managed to just not react to Luffy and his crew, he may have actually succeeded, the sad thing is that he is the most intimidating villain of the original six starter villains, since then he's floating about the seas, as a free man anyway since in the eyes of the world, he's dead but any attempt to comeback in a world of ever stronger pirates and his reasons for wanting out in the first place is being that the world was too chaotic to tirelessly keep going, I think it's safe to say that Kuro wants nothing to do with the One Piece world anymore.