What you describe (doing basic market analysis) is pretty much unrelated to 'rationality.'
'Rationality' hasn't really made any meaningful contributions to human knowledge or thinking. The things you describe, are all products of scientists and statisticians, etc...
Bayesian statistics is not rationality. It is just Bayesian statistics... And it is mathematicians who should get the credit not less wrong!!
The rationalist movement, if it is anything, is a movement defined by the desire of its members to perceive the world accurately and without bias. In that sense, using a variety of different tools from different academic and intellectual disciplines (philosophy, economics, mathematics, etc) should be expected. I don't think any of the major rationalist figures (Yudkowsky, Julia Galef, Zvi Mowshowitz) would claim any credit for developing these ideas; they would simply say they've used and helped popularize a suite of tools for making good decisions.
'Rationality' hasn't really made any meaningful contributions to human knowledge or thinking. The things you describe, are all products of scientists and statisticians, etc...
Bayesian statistics is not rationality. It is just Bayesian statistics... And it is mathematicians who should get the credit not less wrong!!