Irrespective of the reasonableness of the comment you’re responding to, I don’t think this comment is addressing the presented point. My experience with these policies is that these volunteer hours cannot be performed during work hours unless they are coordinated as by a manager in your organization as a team event.

It seems that situation, wherein you cannot reduce or substitute your working hours as an individual to instead volunteer, is what they are commenting on. Parents are being allowed to do this with their parental duties, which seems to be the perceived unfairness.