As a public company, they are legally obligated to pursue maximum returns for shareholders. Given that suing a successful game could potentially bring in more profit than focusing on their own game, there's definitely an argument to be made that they are legally obligated to at least investigate the possibility.
Still absolutely fucked, but yeah, it is illegal for a public company to not pursue profits. It's also possible their contracts obligate them to investigate, though if that's the case, they presumably could waive such a thing with agreement from the developers.