Yes, I knew you were not but you didn't ask about your own bike directly. My answer is still correct and you can indeed push a starnut further down the steerer to let you cut above it.

To keep the starnut square in the steerer while you are hammering it down, put the top cap back on the steerer and run a long M5x.8 mm bolt through it's center hole and thread it into the starnut. The top cap then acts as an alignment guide while you pound on top of the bolt. Also, measure how far you want to lower the starnut and mark the bolt that far above the top cap. Then drive it down until your mark is at the cap.

As with every other cutting job, measure at least twice before getting out the hammer or saw.