Could you give me some suggestions about the test jig?

I am reading the book-High speed Digital Design written by Howard johnson and Martin graham.

There is a test jig for measuring capacitance. In the figure 1.6, when driven by a 2.6-V step input from the source with the DUT diconnected, the nominal step amplitude is 63mV (the scope measures a peak of 67mV).

I think it is not correct. The nominal step amplitude should be calculated by a DC circuit showed in figure 1.7, and the nominal step amplitude in the scope is 31.7mV.

Could you give me some suggestions?

thanks!