scene.dat seems like the obvious place to look but nothing in there does this. Reflection bias, intensity, deformation, fresnel, etc all change the reflections, but they don't remove them.
You couldn't fill a postcard with what I don't know about that file... I thought you might have guessed that. :p
I bet it's hardcoded. Nevermind.
P.S. I don't see a "retire" remark.