I even got the impression that Lelouch blamed it more on the Cult than on Rolo himself, otherwise I doubt he would have been able to keep the act. I think, on the inside, he was aware that it had been partly his fault too, just as he seems to accept when he takes full responsibility for her death in front of Suzaku.
By this I just mean that... I'd say the writers wanted us to empathize with Lelouch's position and thus forgive Rolo like he did at the end... Taniguchi said that Rolo was supposed to be a character "you feel pity for", and seeing how much they love the kid, I can't imagine them wanting to portray him as a remorseless horrible creature. This much is clear, but then again, of course, it is in the interpretation given by the one watching where the true meaning lies, not in the interpretation intended by the creators (that's why literary works can be re-analyzed so many times, isn't it?
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