No, consensual sex with upper management will not always be considered sexual harassment in a court of law. To be “harassing” it has to be “unwanted.” That is part of the definition. It’s hard to prove that an encounter with a subordinate was “wanted” when that person is arguing it was “unwanted”, but that doesn’t mean it is impossible or untrue.
Many of the current accepted standards don't seem logical, fair, or anything close to it, but that is how it is today.