I suspect that your model has been built to serve the hypothesis you started with.
First of all, I’m not sure what measure you’re using for “rigorous thought”. Is it a binary classification? Are there degrees of rigor? I can infer from some of your examples what kind of pattern you might be picking up on, but if we’re going to try and say things like “there’s a correlation between rigor and volume of publication”, I’d like to at least see a rough operational definition of what you mean by rigor. It may seem obvious to you what you mean, and it may seem like a subject many people on this site devoted to refining human rationality will have opinions on. That makes it more important to define your terms rigorously, not less, because your results shouldn’t explain variation in everyone’s definition of rigor.
For the sake of argument, we could use something like “ratio of bits of information implied by factual claims to bits of information contained in presented evidence supporting factual claims” if we want something vaguely quantifiable. It seems your initial set of examples uses a more heuristic approach, with the rigorous group consisting mostly of well-known scientists, artists, and philosophers who are well-liked and whose findings/writings are considered well-founded/meaningful/influential in our current era, and your non-rigorous group consisting of mostly philosophers and some scientists who are at least partially discredited in our current era. I suspect that this might not be a very predictive heuristic, as I think it implicitly relies on some hindsight and also would be vulnerable to exactly the effect you claim if your claim turns out to be true.
Also, I suspect that academic publication and publication of e.g. novels, self-help books, poetry, philosophical treatises, etc. would follow very different rules with respect to rigor versus volume of publication; there are structures in place to make them do exactly that. While journal publication and peer review rules are obviously far from perfect, I suspect that producing a large volume of non-rigorous work is a much better strategy for a fiction writer, philosopher, or artist than it is for a scientist who, if unable to sufficiently hide their non-rigor, will not get their paper published at all, and might start becoming discredited and losing grant money to do further research. In particular, I think the use of a wide temporal range of publishers is going to confound you a lot, because standards have changed and publication rates in general have gone way up in the last ~150 years.
Actually, I’m not even sure how a definition of “rigorous thought” that applies to scientific literature could apply cleanly to fiction-writing, unless it’s the “General Degree of Socially-Accepted Credibility” heuristic discussed earlier.
That’s not exactly true. You can volunteer for far less than the minimum wage (Some would say infinitely less) if you want to. What you can’t do is employ someone for some non-zero amount of money that’s lower than the minimum wage.