Brown doesn’t require subject tests so it’s hardly dishonest not to submit them. Why would the adcoms think it “looks bad” for students to do what they told them they could? You’re a high school senior. Other students shouldn’t base their decision to submit scores based on what you would do if you were an adcom because you aren’t an adcom. There may be different expectations for students from upper income families or certain selective high schools, but those families generally have professional guidance to let them know what those expectations are.