If he is to come in he will buy into the holding company. At least 50/50 but i imagine he will take the bigger share as he will be the principle owner/figurehead.
If he does come in via this route he'll want the authority to make decisions. He's spent a lot of time and money at Arsenal getting nowhere as he didn't have enough of a majority for this to happen.
If he, or Moshiri, want to deal with parties connected with Everton he'll want his board able to conduct that process unobstructed and as easily as possible, both on paper and in practice.