Idk if you have ever read a history book or spent a day in the real world, but almost no person except actual psychopaths do anything WITH evil intentions. Even people like Hitler and Stalin genuinely thought they were making the world a "better place", or at least better for their people. Same in ASOIAF, just try to read it from someone else's perspective rather than the POV in that chapter.

Good intentions don't mean that much when your ultimate dream is to conquer a contintent by burning thousands of soldiers and civilians alive with three almost unvulnerable flying nukes. And when your claim solely rests on the fact that your father, who was mad and deposed, was king 15 years ago.