This is a real hack. I like it.  My main point is that food is the slowest gathered resource. So you can't value it the same as the others in a 1:1 basis. It's also the resource most likely to hit 0 when a player loses. Additionally, the auto train cows part can get a player into real trouble if their food supply suddenly runs low. 

Speaking of which, why don't we just disable the ability to exit a game without resigning? Just turn the button off until the player has resigned.

And I guess one could say it's not even worth the effort in a standard game  

Personally I am fine with this. It is a bit weird and really benefits only in survival of the fittest. Another one is the wonder swapping if you have a ally with diplomacy on: Let the ally capture your wonder, you build a new, change alliances recapture, enjoy having 2 wonders. Now help your ally doing this.

Good. It is easier then.