Need a rule referance and ruling, I can't find one.

[D-Man]

This is a simple substitution and not a pinch hitting situation. At any time, a team can choose to terminate their DH priveledge. In this case the F5 made this decision for them, nevertheless the F5 has been ejected. A team is not required to have a DH and the DH may play defense so he goes in to play third (DH role is terminated) and KEEPS HIS BATTING SLOT. The pitcher is then required, by rule, to take the batting spot of the replaced defensive player.

The DH is not being pinch hit for. He is still in the game and in his batting slot. He is no longer the DH. He is the new third baseman.

The pitcher must occupy a batting slot since the offense has lost it's DH priveledge. There are no more eligible substitutes so the offense has no choice but to put him in the vacated (ejected) third baseman's batting slot.

The ejection makes no difference in this case. If the F5 did not mouth off and the offensive coach wanted the DH to play third (or any other defensive position) then the former DH would stay where he is in the batting order and the pitcher would take the spot of the replaced player, unless the DH was coming in to pitch. In that case the batting order would not change at all. In both cases the role of DH would be terminated for the rest of the game.

D