First, the argument that it is somehow the seller's fault for pricing an item too low. There is no too low - the seller has every right to sell an item for any amount he or she sees fit.
Second, and all else that needs to be said is this:
11 Restrictions and conditions of use:
(B) You will not:
(iii) " use the auction house as an investment vehicle"
Because gold has a real money value associated to it, by flipping items on the GAH, and obviously the RMAH, you are using the AH as an "investment vehicle" and are therefore in violation of the auction house terms of usage.
It therefore follows that Blizzard should implement controls to prevent this from happening, such as timers, or not allowing an item to be re-listed for more than 115% of it's AH purchase price. Since they would simply be enforcing their own terms of usage
You can't compare this AH economy to the real world. It is a video game
How can this be any simpler?