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Tour's critique of universal common descent is that there is no data-substantiated experiments validating the claims regarding the alleged mechanisms creating new complex systems and new body plans. Sure, random variations, natural selection, neutral drift et al. have been claimed as being responsible for creating the new systems and new body plans, but Tour often responds, "Fine, show me the data for this", to which therein lies the present dilemma and what he states that evolutionary biology has been largely reduced to story-telling"
I think this sounds good, but who's to say that things like natural selection, mutations and genetic drift
haven't been demonstrated as mechanisms for macro evolution of body types? I would suggest that they have. People ask for experiments, well, the best we have are things like observed instances of allopatric speciation, things like recorded accumulation and fixation of beneficial mutations by lenski, biogeographic distributions of animals in conjunction with the fossil record etc. Nobody has a time machine to observe hadean microbial origins. All we can do is observe the causes for micro evolution today and accept it as the most plausible means for macro evolution, given an extraordinary amount of time (which we know has indeed passed).
I would say that observation of one species evolving into another in current times is sufficient in justifying macroevolution because macroevolution itself is just a compilation of multiple speciation events. Evolution doesn't suggest that evolution occurs in one generation from one family or order to another.
With that said, why would anyone ask for more? In order to refute this logic, someone would have demonstrate a biological difference between macro and micro evolution. But of course there is none to refer to. Macro and micro are just arbitrary words we use to describe an extent, like long distance vs short distance. But at the end of the day, a foot is a foot and if we see a person take a step, there is no logical means of denying that the same mechanism for taking a step would fail by step 5.
And beyond this still, even if natural selection and mutations didn't account for how evolution occurred in all instances, things like the summation of collaborating phylogenetic trees between things like genetics and the fossil succession really only makes sense in light of common descent.
Which goes back to your comment that a lot of Creationists already accept common descent, which begs the question of what Mr. Tour isn't willing to accept about common descent.
@RTP76
Maybe he himself isn't willing to clarify, else he'd risk refutation.