Ok... and why does he want to stop making money after that?

It was never my intention to portray the attacker as benevolent. I'm sure he wants to flip off the ethereum community for confiscating his funds on that blockchain. Also, endeavouring on actions such as funding an ETC development team serves the hacker's self interest first and foremost. If the attacker can't liquidate without revealing their identity market manipulation is another way to profit.