Well aside from the fact that the Empire doesn't have a clue who Luke is, and I don't recall any sign that Aunt Beru and Uncle Owen do either, they were clearly ignorant of the fugitive status of the driods (which was why they were killed). I'd say his "they are traitors" lacks any evidence to back it up - all the signs are that they were simple honest farmers.
Then we have the Jawas - slaughtered by the Empire, who chooses to disguise this massacre by trying to make it look like a Sandpeople attack. No mention or attempt explain or justify this (I will come back to it though, as it is part of a key issue he ignores and I would say badly damages his line of argument)




Princess Leia: No! Alderaan is peaceful! We have no weapons, you can't possibly...
Governor Tarkin: [impatiently] You would prefer another target, a military target? Then name the system! I grow tired of asking this so it will be the last time: *Where* is the rebel base?
Princess Leia: ...Dantooine. They're on Dantooine.
Governor Tarkin: There. You see, Lord Vader, she can be reasonable. Continue with the operation; you may fire when ready.
Princess Leia: WHAT?
Governor Tarkin: You're far too trusting. Dantooine is too remote to make an effective demonstration - but don't worry; we will deal with your rebel friends soon enough.

By choosing to only quote some of what was said (a small portion of it, in fact) we lose the all important context. Rather than "But the audience has no reason to believe that Leia is telling the truth", we have Tarkin's reply "You would prefer another target, a military target?" - clearly Tarkin sees nothing to dispute in Leia's claim. He is offering her the choice between seeing her peaceful homeworld destroyed or telling him where the military target he is seeking is.
Then we have the final line from Tarkin, clearly he is looking to kill two birds with one stone - if he can destroy the Rebellian's baseworld and demonstrate to all the galaxy the power of the Death Star then he will. He is quite clearly going to destory a central word though even if the Rebels are based as far from the centre as possible - he doesn't destroy Alderaan because he believes "Alderaan is a front for Rebel activity or at least home to many more spies and insurgents like Leia", he destorys is because he needs a planet everyone knows.



Actually it is. As proved by the destruction of Alderaan.



I love how he spins that



'cept when it pertains to "Captain" Solo earlier?




Sounds to me that even with the Emperor in charge he doesn't mind that - as long as he sits at the top, he is happy for local warlords to control the galaxy and behave as brutally as they like.



Ah yes - because we can't see something in around 6-8 hours of film set around military action, we must assume it doesn't happen (rather than the fact that even Lucas perhaps doesn't think he can make a 6 hour debate on how the post-Empire galaxy will be governed interesting). This point is pure conjecture with nothing to back it up but the fact he wants it to be true.



Princess Leia had her tiara under the Empire and there was no sign of her losing it... well apart from as a result of her involvement with the rebels.

He also ignores what is a huge point - species. You don't get to be in the Empire if you're not human (nor, by all appearance not white or male)... and yet both the Republic, to a huge extent, and the rebels, to a lesser extent, numbers of non-human members as well as people of different colour and both genders. Combined with how the Empire massacred the Jawas and tried to disguise that massacre as a Sandpeople attack, I think this clearly shows the true nature of the Empire - a massively bigotted dicatorship dedicated to the supremacy of white males humans, relying on terror and creating inter-species war to maintain control.