The Dharma allows us to separate our discernment (of what is positive and negative) from our emotions. It is not that we will no longer perceive whether something is harmful or beneficial, positive or negative, but that we will be able to maintain a state of peace while perceiving those distinctions.
We can perceive that something is negative, unpleasant, or bothersome as a ‘fact’, but it need not trigger an accompanying emotion of anger. Those are two different mental functions which we may habitually experience together, but are not ‘one’.
We all have had the experience of seeing a ‘negative’ person, object, or event that does not affect us directly, and it did not make us angry. From this we can understand that it is not the negativity of the perception that makes us angry. If that were so, we would be equally angry when perceiving negativity anywhere, and that is not the case.
We may also have had the experience of being angry at someone or something that appears generally positive. The conclusion is that such perceptions of positivity or negativity cannot, by themselves, generate a particular emotional response.
Even martial artists and boxers are trained to set aside their anger while fighting, as it obscures their perception and leads to mistakes and defeat. No one can make a good decision under the grip of anger.
On the contrary, decisions made from a state of peace and clarity are much more accurate. Who deals with a crisis more effectively, a person who is agitated, or a person who is calm? If we were passengers in a sinking ship, would we prefer the captain and crew to be hysterical, or calm and collected, and thus able to communicate proper instructions?
Separating perception and emotion does not lead to inaction, however. If, setting aside our anger, we come to the conclusion (after weighing all factors) that avoiding a particular person, object, or event is beneficial to us and others, then we should avoid it. If it is less beneficial than engaging the experience, then we should engage it without anger, which always clouds reason.