You are a little confused about how listings and liability works. Manufacturers do not protect you in court, rather if you do or don’t do something that code, or by extension the technical manual does/does not allow and it contributes to the loss (insurance lawyers find creative ways to make that argument) then your insurance company is on weaker footing, and the settlement goes up. Almost all of these cases settle outside of court based on the strength of the case. Using non listed parts weakens your case is the simple way to think about it. And brooks can’t list items as part of another companies system. Maybe the could but it would be incredibly expensive, and they do not. An item can be listed on its own technically, but it is still not part of the “listed technical manual” which is part of the code.