Presenting a complex argument requires a whole host of sub-skills.
Nowadays with the internet you can reach billion people, there's a lot of self selection in audience.
On the other hand, you're uncharitable and unnecessarily derogatory.
He's spreading utter nonsense similar in nature to anti vaccination campaigning. The computational technology is important to medicine, and the belief cluster of "AI etc is going to kill us all" already results in the bombs being send to people. No i am not going to be charitable to a person who got good talent at presenting (not as fiction, but as 'science') complete misinformed BS that - if he ever gains traction - will be inspiration to more of this. I'm not charitable to any imams, any popes, any priests, and any cranks. Suppose he was "autodidact" biochemist (with no accomplishments in biochemistry) telling people about some chemical dangers picked from science fiction (and living off donations to support his 'research'). CS is not any simpler than biochemistry. I'm afraid we have a necessity to not have politeness bias about such issues.
There is actual world-dangerous work going on in biochemistry. Every single day, People work with ebola, marburg, bird/swine flus, and hosts of other deadly diseases that have the potential to wipe out huge portions of humanity. All of this is treated EXTREMELY seriously with quarantines, regulations, laws, and massively redundant safety procedures. This is to protect us from things like ebola outbreaks in new york that have never happened outside of science fiction. If CS is not any simpler than biochemistry, and yet NO ONE is taking the dangers as seriously as those of biochemistry, then maybe there SHOULD be someone talking about "science fiction" risks.
I've spent so much time in the cogsci literature that I know the LW approach to rationality is basically the mainstream cogsci approach to rationality (plus some extra stuff about, e.g., language), but... do other people not know this? Do people one step removed from LessWrong — say, in the 'atheist' and 'skeptic' communities — not know this? If this is causing credibility problems in our broader community, it'd be relatively easy to show people that Less Wrong is not, in fact, a "fringe" approach to rationality.
For example, here's Oaksford & Chater in the second chapter to the (excellent) new Oxford Handbook of Thinking and Reasoning, the one on normative systems of rationality:
Is it meaningful to attempt to develop a general theory of rationality at all? We might tentatively suggest that it is a prima facie sign of irrationality to believe in alien abduction, or to will a sports team to win in order to increase their chance of victory. But these views or actions might be entirely rational, given suitably nonstandard background beliefs about other alien activity and the general efficacy of psychic powers. Irrationality may, though, be ascribed if there is a clash between a particular belief or behavior and such background assumptions. Thus, a thorough-going physicalist may, perhaps, be accused of irrationality if she simultaneously believes in psychic powers. A theory of rationality cannot, therefore, be viewed as clarifying either what people should believe or how people should act—but it can determine whether beliefs and behaviors are compatible. Similarly, a theory of rational choice cannot determine whether it is rational to smoke or to exercise daily; but it might clarify whether a particular choice is compatible with other beliefs and choices.
From this viewpoint, normative theories can be viewed as clarifying conditions of consistency… Logic can be viewed as studying the notion of consistency over beliefs. Probability… studies consistency over degrees of belief. Rational choice theory studies the consistency of beliefs and values with choices.
They go on to clarify that by probability they mean Bayesian probability theory, and by rational choice theory they mean Bayesian decision theory. You'll get the same account in the textbooks on the cogsci of rationality, e.g. Thinking and Deciding or Rational Choice in an Uncertain World.