The lord that was doing it felt that the satisfaction of watching others starve was worth more to him than the gold that selling the food would have brought in. In fact, I think he did eventually sell a lot, by demanding that the duke that wanted the food send him extra bonds, on top of the 50/100 sale price. I'm not sure, but I think he ended up getting the equivalent of 100/100.
What are the odds that the price cap could be raised to 100/100? In many cases, it seems like 50/100 is underselling. I don't see any reason as to why it's so low.
