It may not be cut and dry to kill it legally. While they probably could do so on a patent or EULA case, if the guy is willing, it's a lot cheaper to just offer

It may not be cut and dry to kill it legally. While they probably could do so on a patent or EULA case, if the guy is willing, it's a lot cheaper to just offer him a run-of-the-mill salary and employment package. As soon as he becomes an employee, any substantive future contribution to the project is instantly tainted, even if it's just documentation or giving hints to the new maintainers. At that point, Apple would have a very solid trade secret case, amplified by copyright claims and the violation of the prerequisite NDA. Similar projects know to stay really, really far away from anyone associated with the company whose product they're duplicating. WINE wants nothing to do with you if you've ever come within 500 feet of Microsoft's source code. If the project's founder is willing to give up that easily, it's certainly an easy, cheap way to kill off such a project.