First and foremost, from a Naturalistic Humanist perspective blaming cannot be justified. An individual who commits an exclusionary behavior is only its proximate cause, the ultimate cause involves the legacy of domination culture and its institutions. The behavior needs to be recognized as not emanating from them, but resulting from a system from which they need to be freed.
Rather than scolding or criticizing, those who engage someone in such a discussion might try to imagine that they are offering an opportunity for a less aware person to mature and grow beyond their current limitations.
The conversation should try to bridge, no matter how slightly, the chasm between you and the other person. If these are your intentions the person being addressed is likely to sense it. And if they are sufficiently emotionally healthy, they will welcome the effort. A less healthy person, however, may be more guarded and less able to respond.
Anyone, even people who are highly aware and sensitive, can speak or act in exclusionary ways. Increasing diversity means that sooner or later we are all likely to encounter situations in which we might speak or behave in a hurtful manner, even if it is not our intent. Being sensitive to one or several marginalized groups doesn’t make us invulnerable to committing macroaggressions.
If you have been fortunate enough to have had experiences which resulted in you becoming sufficiently aware and sensitive so that you do not make micro-aggressive comments or behave in micro-aggressive ways – that is wonderful, but ridiculing others who don’t share your good fortune is unfair.
A key idea in Naturalistic Humanism is that, given all that led us to a given moment, we are all doing our best, being the healthiest we can. Were you to have the other person’s determinants, you would behave exactly like them as there are no good or bad people, just people with different circumstances. This understanding has many implications for how we should attempt to raise awareness and sensitivity in others.