They're not "back".

David Mackay has already destroyed his reputation as a scientist by first leaping to a conclusion and then struggling with every effort to prove his hypothesis, rather than the standard scientific method of trying to DISprove the hypothesis.

No serious biologist, geologist, or planetologist will ever again credit any paper he publishes on this topic.

His arguments about probabilities are akin to the "blind watchmaker" arguments against evolution and are equally fallacious, in my humble, but scientifically-informed opinion.

If someone wholly independent does work that is actually credible, then that will be a different story, but this man and his team are a public laughing stock at conferences. From time to time a serious scientist will step in and demolish his latest pack of cards, but mostly he is left to metaphorically draw on the walls of the padded cell with soft crayons...

(Science is not blind, and it is important that he and his team do continue to publish their works and thoughts, but most readers are disappointed he cannot move substantially forward from his entrenched position)