Apparently Vince was high on Ahmed for a bit. Then Austin kinda happened.There were physical and political reasons why he did. Ahmed Johnson was better suited for body building, not wrestling. It was obvious that his body was wrongly conditioned for athletic sports. He was always going to be at risk of injury.
Also, WWE didn't have a very wide vision for black people at the time. Faarooq went down in flames and for all intents and purposes, his run wasn't worth much in the end.