I'm still gonna wait for the chapter before deciding if Enma, when activated actually has the former wielder's haki, or if Kaido simply just recognizes Enma, the sword itself and its power.
The issue I have with Enma having the former wielder's haki (Oden) is that with the Scabbards being ready to give up their lives in their fight with Kaido, they could've just used Enma one by one until all their haki is depleted since their willing to give up their lives anyway.
Especially, the Scabbards have planned a surprise attack to assassinate Kaido and it actually worked except that they couldn't cut Kaido deep enough. One of them could've just used Enma in that surprise attack. I think it's pretty safe to assume that one of the Scabbards has one of the 21 Ō Wazamono so they could've just given one of their swords to Zoro in replacement for Enma.