Yes, that would make sense wouldn't it - because by signing him now with 6 months left on his contract he wouldn't automatically, immediately be worth more than any fee we paid would he?
And if we leave it until the summer we'll definitely be able to sign him because there obviously won't be as many clubs in for him when he's available for nothing.
Intelligent thinking from an intelligent club.
Recognising your best opportunities to sign quality players is for other clubs to do, not Sheffield United.