I'll definitely stop short of calling bullsh*t, however I'd really like to see some before and afters or even more ideally a short video showing it. I've used all grades of abrasives, steel wool and Scotchbrites in Green (mostly) but also grey and red. I'm fairly familiar with how they abrade surfaces and I would really need to SEE this not ruining the finish to believe it.
Thinking about it more, IF it's truly slathered in oil AND you can go REALLY lightly I suppose it would be possible to knock down the light surface rust without ruining the finish/ Not a gamble I'd wish to take on a collectible rifle, but I do admit it's probably possible to do this.