So , I still don't understand how unexecuted order can manipulate the market.In my understanding, who cares how many orders are hanging there, as long as they are not executed they shouldn't have any influence on price at all. I only have experiene with retail forex and you can cancel those orders without issues there
He wouldn't be doing it if there wasn't a point to it. The reason he's doing it is to create an order book imbalance which algos will act on and hence he gets filled on the other side. When he cancels orders on the imbalanced side and price moves back.
IMO if "spoofing" were simply allowed it would force the algos to deal with it and make spoofing uneconomical.