Unfortunately, while the idea in itself was sound, he really should not have reached out to Balon Greyjoy, because all that accomplished was planting a seed of doubt in Theon and telling Balon it's prime time for some raiding. Now, a smarter Greyjoy should have went with Robb's plan, but it was just that Balon is a stupid, petty asshole.
That said, even Tywin is guilty of short-term planning. Because he really didn't seem to understand he wasn't immortal and his own succession is a bit...shaky. So, as soon as he was dead and the hostages, once way or another, are gone, they *would* unquestionably rise up again, because he just permanently established the Lannisters as untrustworthy assholes with the biggest taboo in their society.