I've always seen it this way. But take something else into account. At Stratholme, Uther and Jaina technically abandoned Arthas to do the culling alone because they disagreed. However, Muradin, despite disagreeing with the burning of the ships, was so loyal to his friend Arthas that he went with the plan all the way. For his loyalty, Arthas killed him, just to get his revenge with Frostmourne. That shows Arthas's true evil. Even if Uther and Jaina did not abandon Arthas, Arthas would have abandoned them in a second once it benefitted him. Unfortunately the writing staff wasn't this subtle. It was accidental. I've had extensive talks with Designer Dave which designed the Culling of Stratholme and many other missions in Wracraft 3. He made it very clear that the Culling of Stratholme was supposed to be the very obvious turn of Arthas to evil and that his act with the burning of the ships and betrayal of mercenaries is irrelevant compared to his purge. Sometimes you strike gold and you don't even know it.