First be clear, everything I know on this has been posted on the TFC Forum.
I took Trend's post to suggest that what I had called "unusual trading behavior" at least in corn, in the face of the earlier "limit up" that PFG customers were likely closing their long positions.
PFG traders were permitted to close open positions, but not trade.
So, my take is that Trend's assessment was/is correct. Also if this is the case, the PFG clients with long corn positions were reasonably intelligent about closing them out over the day (say mid morning to close). Corn price did oscillate and decline a bit but not a significant drop all things considered.
So, these are my best thoughts at the moment !!
Hope this helps.