Schmidt and company could have told Steve to kick rocks and what could he do. Stop making Google the default search engine for Apple stuff, ask that Schmidt be kicked off the board. Okay sure, go for it. Sue, nope. Not unless they can prove that what Google was doing was illegal.
Schmidt and friends are the ones that decided to halt things, to fire the recruiter and to stop talking to Apple staff from the sounds of things. So that's all on them, not Apple.
I suspect a big part of how this suit will fall out will depend on the nature of the employment contracts and whether they contain valid clauses that would prevent the employee from leaving at the time that they were being actively recruited. If this is the case then the recruitment could be seen as encouraging said parties to violate their contract by leaving, which is not so cool. Another big part of the game will be if what we are talking about is not chasing after active employees or agreeing to turn them away even if they approach the company to change jobs (the latter I totally agree is and should be a no no)
You don't understand the legal definition of "conspire".