The phrase "took side" means to have chosen a particular stance, opinion, or group. Antonyms for this phrase would include: impartial, neutral, unbiased, objective or indifferent. These words suggest a lack of bias or influence, or a position of neutrality, rather than taking a side, as its opposite would imply. Opposing words could also include "abstained", which is to refrain from taking a side altogether, or "betrayed", meaning to have abandoned or turned on a side that was previously taken. Regardless of what antonym is used, these words are used to describe a lack of taking a side or choosing a stance.