alright waltergodefroot...since you want to bring up a fringe example...will test your knowledge further. Do you know why a steerer tube is extruded and butted in the first place? Lastly...honing a butt welded seam that is proud to the I.D. of a steerer will NOT diminish its strength as long as machine honing does not exceed the overall parent wall thickness requirement. What you wrote is simply untrue. Your scenario is for naught 95% of the time anyway...even if retrofiting butted steerers meant for a big bike onto a bike with shorter steerer that is cut down because as syd mentioned, you can shorten the quill to minimize penetration.
George