It certainly wasn't 'conservative' given it called for a radical restructuring of German society, and many aristocratic conservatives were contemptuous of Hitler.
It's rise was aided by conservative elements of German society though as they thought they could use it for their own ends against the social democrats and socialist, but ended up seriously underestimating Hitler.
I agree that there were aristocratic conservatives who were contemptuous of Hitler, but were they contemptuous of his politics, or just the fact that he was a corporal from a lower class? The kind of nationalism Hitler preached was mostly derivative of the same malignant nationalism which was favored by the aristocrats and was quite prevalent since at least the Franco-Prussian War of 1871.
They all enthusiastically served the Kaiser, who was an anti-Semite and malignant nationalist, just as Hitler was, even if not quite as extreme. So, I think their politics were probably similar to that of Hitler, but it may have grated on their egos to have a mere corporal elevated to position of supreme leader. Perhaps they felt he was the lesser of two evils, considering that actual communists were a formidable political threat at the time. Maybe they thought they could control him.
After the war, they were all saying "we didn't know" or "we were just following orders," but I don't think very many people actually believed that. They may have been contemptuous of him, but they still chose him. The communists were the only ones openly challenging Hitler and fighting Nazis in the street. They were contemptuous of Hitler, too, but they didn't get any help from the German aristocracy, as Hitler did.
It should also be noted that a lot of early social reforms were favored by German aristocrats. It was similar with Napoleon III, who favored a more nationalistic program, but was also a social liberal in supporting pensions, old age homes, and other social programs which gained traction in other countries. They were "liberal" in the sense that they believed in taking care of their own people, but also nationalists in their campaigns to screw everyone else. But it had nothing to do with Hitler; these were programs already supported by German nobility.
I believe the English aristocracy also supported similar social programs around the same time. In the US, Teddy Roosevelt's "New Nationalism" and Woodrow Wilson's "New Freedom" both contained support of social programs and promised a better standard of living. It wasn't "socialism," as such, even if it might have contained some elements of it.