According to the Orkneyinga Saga, Matad was the son of Máel Muire, who was son of king Donnchad I and younger brother of King Máel Coluim III Cenn Mór.
It is highly unlikely that the kings of Scotland, with little more claim to the kingship than Matad himself, would have been in a position to "grant" the Mormaerdom.
Mormaer Matad is most famous for being the father of Harald Maddadsson, or Arailt mac Mataid.
He married Margaret, the daughter of Haakon Paulsson (the son of Thorfinn the Mighty).
He also features as a witness to charters of the reign of King David I, where he is called Madeth Comes and Maddoc Comes (=Mormaer Matad).