Part of the wisdom factor of the mind is learning how to discern what is beneficial, what is unbeneficial, what is skillful and what is unskillful. If we let go of all judgment, then we cannot discern what is skillful or unskillful, what is beneficial and what is unbeneficial. Judgment does not necessarily mean that we do not have compassion for others, but it's actually clearly seeing, for example, the action, and if we see the action is causes Dukkha then it is wise to judge it as unskillful. But we also see that many times the person doing the action is ignorant, particularly of the unskillful Kamma that they are making. If we let go of all judgment, we cannot protect ourselves in the world. So part of the wisdom faculty is learning how to be discerning about what is skillful or unskillful and what is beneficial or unbeneficial. And we have to continuously discern that within ourselves.
In fact, in the Rahulovada Sutta , the Buddha asks his son to reflect before he does an action, while he's doing an action and after he's done an action. We can apply this to our own actions. To know whether it leads to our own affliction, the affliction of others of the affliction of both. Is it skillful or unskillful? Does it lead to happiness or suffering for ourselves or for others? This is part of the wisdom mind and how we actually purify our actions, speech and thoughts.
In the fourth Foundation of Mindfulness, especially in the first section of observing the hindrances, we observe the hindrances internally and externally, that is, also in others. This is not to form aversions towards them, but to help in discerning what is skillful for ourselves, what is unskillful, what we want to do and what we do not want to do. And if we have the capacity to help another person to go away from unskillful action, then we try to do so. This also involves what the Buddha talked about in judging for oneself whether or not a person is open to instructions. How can we do this unless we are discerning about their actions, speech and thoughts? And judging for ourselves whether they are capable of understanding. So it actually does help us to make a determination in ourselves when we see an action that is unskillful to try to prevent that arising in ourselves.