I think that the one who had that 30K BTC and sold into that 5K BTC wall is a legit seller and not a manipulator.... the minute he saw that Bid wall he saw a chance to sell off some of his stash and he did put the ask wall thinking that someone will eat into it.

Ok, so why did he remove it after a short while if he is a legit sell, and build up that 8000BTC bid wall....
and why didnīt he slowly sell out over all exchanges distributed.
Sorry but your explanation is highly unlikely.
There is a big possibility that he is verified only at Bitstamp (in instance I am verified only at stamp), the other possibility is him selling for the available 5KBTC and watching if anyone is prepared to buy his stash which eventually failed, and I think he did remove that Bid wall to not cause more panic.... after all, I think he still interested in selling even more, we will see how things develop when more bids build up.
If he wanted to sell, he would have called, GABI, Tim Draper, Barry Silbert, some other OTC exchange, or just dump them all in one go. But not by placing walls on a sunday!
maybe he wanted some entertainment value. maybe he called them and they said no, or gave him a bad rate. maybe he is drunk and found out his g/f was in a gang bang last night with his brother...
you don't need the reason, the fact is there is a wall, there is a person who is trigger happy, and could shit on your trade at any moment.