If someone was bullying you and picking on private details about you, would you want them to be seen publicly? No.
If someone sent you an inappropriate picture or link, would you allow everyone on the forums to see it? I hope not.
Making private reports not allowed wouldn't even be possible, people could still report privately on Discord, Twitter, Instagram and conversations anyway. The staff won't just say "No, we don't accept this report. Report it publicly."
In Lachlan's case, everyone would go off at whoever posted the report and the reporter would have to deal with unnecessary comments. Even if it were a false ban, it is up to staff. No matter what. Public reports, private reports, it's always a staff decision so I don't see the problem in private reports. You may want to put your two cents when it comes to reports like Lachlan's but we have a staff team for a reason. If you noticed something off about a report, someone in the team is bound to notice it too, like edw in this case.
But this is just my opinion, of course.
Thanks for coming to my TEDTalk xD