With respect, you and your company of people who are already subject matter experts are not his audience; his audience is people who are not experts and want to learn about this subject matter. Most people on HN are also not subject matter experts with respect to rockets, so in that respect, are probably much closer to his target audience on average than you are.

> He is not a rocket scientist.

That might well be a pro, not a con. Rocket scientists' core competency is designing rockets, not teaching, and subject matter experts often make poor teachers. If this were a case of some kind of hucksterism, where he's an ignorant layperson making shit up and passing it off as true in his educational content, I'd say there was some concern, but while he's apparently said some dumb shit on Twitter, it doesn't seem like you or most other commenters are pointing to anything factually inaccurate _in this article_, nor indeed do people tend to on his researched, long-form stuff generally (vs. some off-the-cuff tweet). In that sense, it seems like this content is as good a place as any for laypeople to learn about this topic, that it doesn't obviously suffer from his lack of formal training, and maybe benefits if it means his better able to translate technical content to non-technical audiences.