Duh, could it be because its federal law and the executive branch is responsible for carrying out the law of the land. The regulations are written by HHS in order to implement laws passed by Congress. Deciding not to write regulations, doesnt eliminate his responsibility to carry out the law. Presumably in your questioning mode you want to know why he doesnt just get congress to rescind the act. Fat chance of that happening. Apparently you want him to attack "windmills" because it supports your ideology, not because its going to make any difference in the real world.