Would you say he set those walls to influence the rates ? ( many people will put orders in front of his, so price is unlikely to drop that deep as it would without those walls )
What could be his strategy ( if any ) ?
Of course a big order like that on a small exchange could influence people to buy at higher rates like you said. But I don't think he pushes the price, because kraken is one of the lower € price at the moment (btc-e 593€, bitcoin.de 589€, kraken 583€).