Antonyms for the phrase "was in favor of" include "opposed to," "against," "disapproving of," "unsupportive of," "critical of," and "uncertain about." When someone is not in favor of something, it means that they have a negative perspective towards it. For instance, if someone is opposed to a particular agenda, they disagree with it or feel that it is not the best course of action. Meanwhile, when someone is critical of a particular decision, they might be pointing out that there were better alternatives to it. In summary, antonyms for the phrase "was in favor of" describe situations where there is dissent, disagreement, or negative opinions about a subject.