You know they did that in the treasuries markets too right?
Meaningless to your probable point you are trying made unless you look at the specifics. What if that manipulation had no directional bias over a period of time. Whoops! There goes the gold bug conspiracy rants that they are suppressing the price of the silver/gold markets.
Traders and firms will always try to gain an advantage over other traders. I personally think spoofing should be legal. If the other guys trading algorithms are written so poorly that they can be faked out that easily they deserve what they get.
So you know your competitors have computer trading systems looking at the depth chart and adding up bid and ask volumes for X number of layers. Then their trading algo will trade from a buy or sell side bias. Why not fake them out? To me, that’s part of trading. Why is that any different than putting in an order and hiding from the tape the true trade size, i.e. you are selling 50 thousand shares but only show 5,000. Same effect as spoofing.