I just think it would entirely fly in the face of what we currently know mantles to be, admittedly incomplete thou it is, that he can just set it aside here and there.
In a sense of power, yes. But in a sense of identity, I think the scale of difference is not dissimilar to Harry being extended invitations as "Harry Dresden, Winter Knight" or "Harry Dresden, Warden of the White Council"; it seems clearly in earlier books that him being in certain situations as Emissary of Winter has different significance to him being there when invited as a Council member though he does not stop being a Council member while he is Emissary.
If the Kringle mantle could be 'set aside' then the same rule as Vadderung could apply, Mab summons him and he shrugs saying 'i'm not Kringle today, try again later.' and then what good does that do anyone?
I'm not seeing that a way to have a smart and powerful and really dangerous player on your side when he wants to be is particularly less useful than a way of calling him to your side whether he wants to be or not, whether it antagonises him or not.