First you can't be sure if it's a script kiddie aka scidiot that did this. Since we can't be sure that it acctually was the original hacker that infected the servers or if he published a script and peoples started to use it and then infected the servers. But your right my guess is that its the hacker that did it.
Second, I absolutely don't agree with you on this one and when it comes to that "He could have made the exploit worse" part that just an idiotic resasoning. You can easily translate this situation to IRL.
Let's say you have 1000 $ in your house.
You dont lock the door everyday when you leave the house.
Someone notices this and goes to your house, open the door get's in and takes 300 $ of your 1000 $.
Later on the thief is catched.
Now would you then say, in court: "ooohhhh it wasn't that bad. He made me and my neighbours a favor. He didn't take all, He left 700 $ and just pointed out that I had a security hole that someone further on could exploit by opening the door and take all of my money....."
It's still a crime to get in to your house and steal the money right?
The way of saying "it's for the best of the public" is just a way to try to justify hacking/black hats/grey hats and it's always the same thing. When someone hacks a website, a internetbank, a government, a households computer or what ever it is. It's always the same story "He/She was just pointing out security holes so no one else could explot them further on....."
I've been a network IT security consultant since 1992 (yes that's right, I'm an old dude but I can at least say that I was part of creating the Internet boom) and over 21 years I've heard the same story over and over again. "We just did it to show the exploit to make sure that no one else exploited it later on, it was for the publics best" and in trust me on this one. It's never in the best of the public.....
If you find an exploit contact the issuer of the software/game or what ever it is. If you don't get a respons, publish how it might be done, in this case the forum. That's the best of the public.
As someone else was ponting out on the forum. Some peoples (thats the public) are paying mney to have a ARMA3 server up and running and now they can't play on the server......