Blades boss Kevin Blackwell said: "We don't have to let him go and so we won't be. Kyle is not taking part.
"He would be away for a long time, and for a crucial time, and we don't believe it would be in either his or our best interests.
"Kyle doesn't have a problem with it. He agrees with us that he is better off staying here and continuing to represent this club. There are no difficulties at all."