If Jeff had said that there were letters from home involved, that deal never would have been struck. I'm guessing that when the other tribe finds out (probably after the merge) that they're going to be gunning for Penner for 'stealing their mail from home.'
Penner probably calculated out the number of players remaining, likelihood of a three person ending, and figured a merge was possibly right before the immunity challenge the next day. Worst case scenario, they would be without rice for a couple days until the merge. Seems like a smart deal to me.
I can’t remember if the game gives a new stock of food staples after a merge, but if not, do you see the other tribe willingly share the rice (if there is any left to share)? The boat and fishing gear may sway them to the side of generosity I guess. I also was wondering what happened to the remaining rice from Malcom and Denise’s camp. Was it divided up or returned to production? Just some of the strange stuff that floats around inside my head.