This has nothing to do really with the question that Troels asked,
but the exposition quoted from the AA paper is unnecessarily confusing.
The phrase ``Because X0 and X1 have identical marginal
distributions ...''
throws the reader off the track. The identical marginal distributions
are irrelevant. All one needs is that the ***means*** of X0 and X1
be the same, and then the null hypothesis tested by a paired t-test
is true and so the p-values are (asymptotically) Uniform[0,1]. With
a sample size of 100, the ``asymptotically'' bit can be safely ignored
for any ``decent'' joint distribution of X0 and X1. If one further
assumes that X0 - X1 is Gaussian (which has nothing to do with X0 and
X1 having identical marginal distributions) then ``asymptotically''
turns into ``exactly''.