Yeah, I never asked them, but I guess they have to assume everyone is an idiot and so they say dont do any modifications. But you are only removing very minimal material out of the stock, so not affecting the structure.
I didnt get the folder as they are not legal in all states of Australia. Mine is the fixed stock with the integral ARCA rail. You may have an issue with the bolt on a lefty interfering with the folding stock?
This is a photo of my ARC Mausingfield long action 300 Norma. Same deal as the other photo, just a RH converted to LH.