He thought they had the game won and made the move for defensive purposes as Clemson only needed 2 outs to win the game.
For folks that don’t know, Grice was the starting 1B for Clemson when he wasn’t pitching. Amick only played 1B when Grice was P. So he moved Grice from P to 1B and put Amick on the bench. This lost the DH for the remainder of the game since Grice was DH’ing for himself as P. Since UT tied it up, Clemson was forced to pitch hit every time their relievers came up to bat. Turned out to be a horrendous decision for Clemson and the impetus for Amick entering the portal.