That's as deep as it gets, people.
He wrote that "I’ve yet to see any [death threats] that have been substantiated" and asked for substantiation. I provided this article, and Watts again asked for evidence. I gave this list, which ("snip") he refused to allow to be posted. Then I posted this recent video from Australia, the most obvious evidence of them all, and he still refused to allow it to be posted -- four times: "snip", "snip", "snip", "snip" -- the last time because I did not apologize for not providing evidence of the threats, which he did not allow to be posted!
He again asked for evidence on a later post. I offered all these articles, especially this article from The Guardian which directly quotes from some of the threatening emails. His reply would have made a birther proud:
I’m familiar with these, but none of them show anything to make me believe they are real. I can just as easily create a list of complaints without email headers of any kind and “claim” that I get death threats here at WUWT or that I had a dead animal dumped on my doorstep.... If somebody shows me actual emails, like in climategate, then that would be evidence.Of course if such emails were made public (and what threatened person would do that anyway, with all kinds of private information in their headers?) his excuse would be that it's easy to type up a fake email message in a flat ASCII file.
So there really is no evidence you can provide. None. Even in principle. (For good measure they then again disallowed a link to the Australian video.)
You literally cannot even begin to reason with him. His denial has no bottom and is now maintained by outright refusal of facts.
Is there even a word for this level of craven depravity? It would be hilarious if it weren't so dangerous. But it is very, very dangerous.