The TT length means nothing without the STA to go with it. The two work together to create the reach of the frame.
I don't think much of the CC fit calculator either. Too easy to make errors in the measurements and the results don't list a STA to go with the TT length. No fit calculator has any way of knowing if the rider can tolerate a 5cm drop or a 12cm drop. That could make a big difference in the frame size chosen.