This argument, more from psychology than philosophy, does not present a moral criticism but does portray forgiving as negative. The gist of the argument is that forgiving always commences after injustice. It does not prevent injustice from happening in the first place, and so it is a passive form of communication and action.
Our response is a question: What is effective in stemming injustice in this imperfect world?
No form of communication, no problem-solving strategy to date, can prevent all injustice. Is it not reassuring to know that there is a potentially helpful response to injustice after it occurs?
Furthermore, we must ask why forgiveness is considered passive just because it comes after an injustice. When one examines the struggle to overcome anger, the struggle to offer undeserved compassion to an injurer, one can hardly label forgiving as passive.
Finally, as one forgives, is it not possible that the offender may be transformed through the forgiving, thus making that form of injustice less likely in the future? In such cases, forgiveness precedes issues of justice and injustice and acts as a preventive of further abuse.
Enright, Robert D.; Fitzgibbons, Richard P.. Forgiveness Therapy (Kindle Locations 5225-5234). American Psychological Association (APA). Kindle Edition.