The difference between conservatives and liberals is that conservatives will enforce a law on the books, even if they dislike it, because it is the law. Liberals will just thumb their nose in the wind to a law they dislike, or even tell cops to ignore violations thereof.
Except in this case, the 'conservative' in question went against the wishes of the conservative administration, the last one as a matter of fact, at the time. Beside that fact, I find any argument that the national government has the right to determine the speed limit in the separate and sovereign states to be specious at best. Dole believes it is the right and responsibility of the national government to protect us from ourselves. Doesn't sound very conservative to me.