Right so that brings me to the crux of the issue that needs to be addressed.  You are right, these informed traders were not
I largely considered the activity of buying low on the internal exchange and selling high on an external one as irrational, as the barrier to entry cost to trade on the internal exchange is minimal, I (perhaps incorrectly) assumed that no one would buy at the higher external price.  (Are there even any valid reasons why they would?)