You are correct that it would constitute a conflict of interest to sell components that the seller is reviewing. When Bicycle Quarterly reviews a product that they sell they disclose that in the article. In this case, I found no evidence that Jan Heine sells any generator hubs on his website, and he does not operate a bike shop. He did disclose that one of the reviewers works for the manufacturer of SON hubs. You will also see that he invited Shimano to respond to his test results. This is what Jan says about conflict of interest: Q:“Doesn't that constitute a conflict of interest when you test these and other components for Bicycle Quarterly?
A: That is a real concern, and we are very aware of it. Our rule is simple: If a product is extraordinary, we sell it. So we usually first test components, and then decide whether to sell them. If we find new extraordinary products, we sell them as well. That way, we have no incentive to criticize components that compete with the ones we offer - we just offer them all. In many cases, the components we sell would not be available in North America otherwise, because the profit margins are too small. We feel that our readers are better served by having these components available, than if we told you about these fabulous parts that you cannot get. We disclose all potential conflicts of interest with each article. Our readers then can make up their own minds. Our main business is publishing Bicycle Quarterly. The components are only a sideline, so we don't feel the need to promote them excessively.With everything we test, we try hard to be objective. If anything, we are more critical of the products we sell. In our test of the Grand Bois "Ourson" tires, we said they weren't worth the extra money over Panaracers, because unlike other Grand Bois tires, they use an older tire mold with a less-than-optimal tread pattern. Conflicts of interest are unavoidable, because the cycling world is small. Most makers of "real-world" bicycles know each other, and many are good friends of ours. This close collaboration improves the quality of the bicycles they offer, so it is a good thing. But it means that conflicts of interest are unavoidable. It's actually a lot easier to criticize a component we sell than one sold by a friend!”
My original point was that just because you have a different experience does not mean that it did not happen to someone else and is not sufficient cause to question someone’s honesty. Questioning methodology however is fair game.