Abandoning the pretense of objectivity does not mean abandoning the journalist's most important obligation, which is factual accuracy. In fact, the practice of opinion journalism brings additional ethical obligations. These can be summarized in two words: intellectual honesty. Are you writing or saying what you really think? Have you tested it against the available counterarguments? Will you stand by an expressed principle in different situations, when it leads to an unpleasing conclusion? Are you open to new evidence or argument that might change your mind? Do you retain at least a tiny, healthy sliver of a doubt about the argument you choose to make?
Amen to that.