I must confess that I'm not particularly conversant in the science. I do think that some of the examples of fine-tuning that we have are rational evidence that our specific physical laws are not unique and that some regularities will have no deep explanation (just the anthropic kind). For the purposes of the paper, I take most of the fine-tuning argument for granted in order to allow for a focused discussion of the objection I'm interested in.

(FWIW, my meta-impression of Stenger's stuff on fine-tuning is that he is mostly taken seriously by pop atheists. He might have other fans that I don't know about though.)