Maybe because the Klitschko's want to not get ripped off and keep the money they work hard for and deserve? K2 doesn't need King. Never have.
Watch the movie of the Klitschkos then you will understand. They understood that Don is not an honest person, the Klitschkos, especially Vitali, are clever and wise unlike so many boxers who signed with DK.
King tried to sign em various times.. Arum as well but the Klitschkos want none of any other promoter and just do their own business. when King signed Kotelnik one of them came out and was on about what a fraud DK is and how Kotelnik will badly regret signing with him. DK also made a big offer regarding a brother vs brother fight a couple years back. Solis was also with King when he fought Vitali..