I have a fairly nice pipe cutter like that, and I would still be very hesitant to use it to cut a steerer. If you're not paying attention you'll make a revolution and find that you'll make a rotation and realize that you're not where you started, making a spiral instead of a circle. I would feel more comfortable with a saw and a clamp-on jig.
It can certainly be done, I'm just fearful of an ADD moment screwing up a fork.