The antonyms for the phrase "acts as a witness" can include "ignores," "disregards," "overlooks," "neglects," or "avoids." These words all connote a lack of attention to detail and responsibility when it comes to observing or reporting events. Choosing to ignore or overlook an incident, rather than acting as a witness, can leave others vulnerable and without the support they need. Neglecting to act as a witness or avoiding the responsibility altogether can lead to negative consequences for all involved, creating a lack of accountability and trust. In contrast, acting as a witness demonstrates a willingness to take responsibility and provide support for others.