Science is supposed to be about the search for truth, and the test of results, all via methods that make it likely that facts and truth have been discovered (see Karl Popper for more). Scientists are of course entitled and encouraged (as are all human being) to have opinions on political and social issues which go beyond science. There's nothing whatsoever wrong with a scientist saying I, as a scientist, have such and such a political view, for the following reasons. Nor is there anything wrong with scientists or anyone agreeing or disagreeing with a political view because they think that view runs contrary to science. Indeed, expression of such disagreement is a public service.
But there is something harmful in presenting political views, and social forecasts, in a literally numerical package which, frankly, feigns the imprimatur of science. Hari Seldon's psychohistory sought to do that in Isaac Asimov's Foundation trilogy, but that is superb science fiction not fact.
The fact is that the metaphor of the clock is just that - a metaphor. Two and 1/2 minutes to midnight has no more correspondence to the reality of present or future than does 3 minutes or 30 minutes. It is just a clever way of calling attention to concerns that scientists have - scientists who are not Hari Seldon, and therefore have no better mathematical way of predicting the future than anyone else outside of characters in science fiction.
And it hurts science, and the public's confidence in it, precisely at a time when we most need it. Scientific research and models which show climate change come from real evidence and events, and we need that respected as such. The Doomsday Clock is a dramatization of understandable opinions - opinions which I share - but which ought not be presented or even implied to be in any way the result of scientific research.
Indeed, to present such as concerns as science is in itself a form of fake news, which thrives in making the boundaries between science and opinion even less clear than they now are. I think the best thing that can be done with the Doomsday Clock is retire it.
more about fake news here