This over simplistic characterization doesn't even come close what this debate is about.
Nobody thought Falwell/Robertson didn't ultimately blame the Islamic extremist terrorists for the act of flying airplanes full of men women and children into those buildings.
It was their disgustingly pious pronouncements that this was also God exacting judgement against groups they personally don't like.
Their comments against Islam in general are not necessarily aimed at terrorists alone and have been criticized for entirely different reasons.
Your claim that these two positions are mutually exclusive and that one can criticize them for one and not the other doesn't even make sense.
By the way, Falwell apologized in BOTH instances.