So what? They're already getting sued by Apple, so what's another lawsuit? Point is, contract breach or not, Samsung could cripple Apple's whole ecosystem within days by halting all processor shipments.
Big businesses aren't usually personal. Law suits happen, it shouldn't mean it turns into fisty-cuffs!
(Breach of contract isn't simple, if Samsung did pull out and cripple Apple they could be made to pay damages to cover for that as it is foreseeable. It is obviously much more complex than that, but you get the point.)