I had missed this. Lowder offers real reasons for Dawkins' refusal to debate. I'd take it a step further, and say that even a philosopher of religion can do a disservice to his position if he doesn't have the ability to operate within a debate format. There are good philosophers of religion, both theist and atheist, who would fit in this category.
However, Dawkins a) has gone away from actual science to doing philosophy of religion, however amateurishly, b) engages in a intellectual crusade while systematically avoiding genuine engagement with people who take the position he's crusading against. It isn't Dawkins' failure to debate, it's the way he refuses to debate that I find objectionable.