If you deem slavery as an usable punishment, then all you do is prove Kaidou right. You cannot really imply that Kaidou was evil for being a slaver if you use his same methods to depose him. His interests lied in the beast pirates, not Wano’s citizens, rather, it stops being a moral issue and becomes a power (or lack thereof in the case of Wano) issue, with Kaidou being right regarding how strength controls the world and enslaving the people of Wano was a problem only because Kaidou did it first, rather than Tama.
Besides, what even are the gifters? No name fodders with a family to feed, what would be your standard in making them “worthy” of not being enslaved? Rebelling against Kaidou’s tyranny and meet death? Splendid.
Kaidou the slaver has been deposed, Mr “Drums of Liberation” who suggested Tama to enslave Speed and those guys in the Udon Prison? Won’t face any consequences, because Luffy fans want their cake and eat it too regarding this mess of a character, saying that Luffy is a good guy, the embodiment of freedom, who saves people in other Countries, while at the same time he’s a pirate and will do whatever he wants (including acting like a Tenryubito, ah, but it’s different, he smiles, you see) and Oda just wants to rush to the end, regardless of the consequences of the actions thought up to help Luffy speedrun the defeat of opponents he should (never) even be able to touch.