Yeah, I am not seeing the whole Hakuryuu being more 'realistic', while Alibaba and Aladdin are the only ones that are naive.
Good things can be born out of revenge circumstantially, but that doesn't mean Hakuryuu should be getting any credit. I honestly don't think Hakuryuu gave a shit about the repercussions of his actions at that instant, or if he even thought it through. He probably just killed Madaura he felt like it, and then came up with some bullshit post rationalization. The fact that he was manipulated by Madaura more so than the others is proof that, if anything, he is less mature than them. I still haven't forgotten how big of a crybaby he was before he obtained Zagan's power.
Also, him securing Sinbad's support doesn't mean much because Sinbad is most likely playing him for his own reasons. He has probably been looking for a way to strike at Kou (and Al Thamen) first without having Sindria appear hostile. Aiding the 'rightful' prince who makes the first move is tactically and politically a lot better than having Sindria directly attack.