he's full of it, there is no way the wheel is "coned" enough to make up for the differential effect of the wheel and axle on a train car, there isnt enough side to side flange clearance for it to move enough for one, and two there isnt enough "cone" to the wheels to really make that much difference, gotta remember wheels are steel, its steel on steel and they are turning, so in my mind it would just slide to make up for the differential, but maybe I have no idea what Im talking about... I grew up around trains though
here is a wheel, clearly you can see that there isnt really much "cone"
and its travels in pretty much the exact same spot on the wheel, given the polished steel effect in the center and the build up of crud toward the outside on the lower part of the wheel