Not very quick on the uptake?
Lulu before he got the Geass was filled with brooding rage at the Imperial family and the Empire in general. He was planning, at some point, to set in motion a plan that would topple them. His rage made him not care about anyone who would get in the way of his plans, and not once did he have a moral contradiction like Suzaku did.
Suzaku, having lost someone as important to him as Lulu's mom was to Lulu, is now filled with the same latent anger that Lelouch has felt for most of his life. He now no longer seeks justification when fighting Zero, he just does it out of hatred. No more moral contradictions.
As such, Suzaku has arrived at the point, morally, where Lelouch WAS at the beginning of Season 1. Lelouch was kind of putting his plan or whatever he was doing, off. Its debatable whether or not he would have done it at all. The Geass jumpstarted his efforts and now the results are plain to see. Suzaku, being at the point where Lelouch used to be, with the notable difference of having the ablility to change things without a mysterious superpower (other than defying the laws of physics) is going to be a real pain in the ass when he too gets a Geass.
There, I've spelled it out for you.