I do agree that the Magic stand a better chance to win with Gortat in the game, but I don't think he should be taking Howard's minutes.
The Howard / Gortat combo should have been countered by Doc with Rasheed b/c Rasheed can spread the floor and get defensive rebounds, but for some reason he chose Davis. While Davis had some great plays in the second half, Gortat abused Davis on the offensive boards b/c of his height and length. The perfect example was that sequence where the Magic got about 4 straight offensive boards, compliments of Gortat being taller than any Celtic on the floor. Hopefully Davis, and Rasheed, do a better job of putting a body on him.
Again, Gortat should get more minutes, but over Rashard and not Howard.