The "problem" is not created by the downtimes, it is created by sellers putting players on sale for a low fee under the delusional expectation and assumption that it will drive prices up.
I think it is a lousy excuse to say its the users fault if he gets hurt by unforseeable server downtime. For some players you will get much more money if you start bidding at a lower price, so this is and will be a viable strategy.
A simple solution (we will never see, though), would be to let the seller set a reserve price, so if his price target wont get matched the player will remain with the team - even if there were bids on him.
The counterargument is that no player has sold at less than his listed price. If there's a price you feel you want and won't accept less than that, there's already a perfect mechanism for that. If you list at a lower price, you can get more or you can get less. Having downtime interrupt a potential bidwar sucks, but not enough so to implement a system that can punish someone who has a winning bid, expecting to get their player, and then finds out that the auction meant nothing because no reserve was met.