The City captain will now have to watch the fifth round F.A Cup tie against his old club Newcastle from the St James' Park sidelines after picking up a three-match ban for the sending-off.
"I have never tried to make any excuses for the eight sendings-off and I will not be making an appeal against Stuart's red card even though it was probably harsh," Keegan confirmed.
"I know Stuart would have loved to play at St James but he just has to take it on the chin. We have lost Ali for that match as well and both needlessly.
"I will have to find someone to play in Stuart's position and they will have to try and do as well as Stuart has in the last 20-odd games. He has been tremendous."