So, point out where he is wrong. Admittedly, I'm not a biologist (just a Ph.D. chemist), but AFAIK, his summation of the "state of the science" is right on target.
As ole Justin Wilson would put it, "I garontee" that if there had been even ONE successful use of embryonic stem cells, it would have been front page news in 3-inch high letters.
Thus far, the pro-ESC arguments are all theoretical, not backed up by facts, whereas the ASC arguments are based on multiple real-world successes.
Any appeal to utilitarian aspects of the debate is dangerour because it moves the terms of the debate onto their ground, rather than ours, which is the principle that killing for spare parts is intrinsically and universally unaccepable. So long as the argument is pragmatic, the pro-death side will always be able to argue the need for more research and better technique.
Thus far, the pro-ESC arguments are all theoretical, not backed up by facts, whereas the ASC arguments are based on multiple real-world successes.
I won't dispute it. However, there are some very real theoretical advantages to ESCs over ASCs -- Kellmeyer's own article makes that point (if only to note that there are technical hurdles still to be overcome). Note also that the advantages of ASCs were also theoretical at one time -- so the fact that no ESC treatments currently exist, is not necessarily meaningful to the discussion.
Which is to say, it is not enough to hang our hats on "it doesn't work." Given time and money, it is very likely that some practical ESC-based treatments will be developed, just as has happened with Adult Stem Cells. It is also likely that the ESCs and ASCs would not be useful for the same things -- so we can't simply treat them as interchangeable approaches to the same set of problems.
We have to be honest, also, about the fact that one cannot help but be attracted to the medical possibilities, should ESC pan out. (That's the nature of temptation: it doesn't work if the potential results aren't attractive.) Once ESC does pan out -- as it probably will -- we will be hard-pressed to oppose it on anything other than moral grounds.
The utilitarian argument really does fail the first time a successful ESC treatment is found. That's why (just as with abortion) our only hope is to bolster the moral case against it.