My answer: Definitely not. This is a conflict of interest. Even if the reader of the news story had no prior knowledge of the opinion piece, the journalist should know that this is a breach of media ethics. If a journalist's main objective is to be objective, then this dilemma convolutes the boundary between objective reporting and subjective opinion. Once your opinion is published and floating around the interweb, people know your stance and that can distort the accuracy of your reporting from the reader's perspective. Now, don't get me wrong, I believe a professional journalist is fully capable of writing an objective news story after having written an opinion piece, but capability is not the issue, it is fairness to your readers so that they have no way to be skeptical of your objective reporting. In an age where readers are skeptical of the news already, it is important and ethical to set these boundaries in the newsroom.