You're missing the point. I don't care if it's an exploit or misconfiguration. They can be doing their job and over look stuff. It's EASY to overlook stuff. So it's not like the admins were slacking off and not caring about their job. Maybe they were, but you cannot know that.
Rather than risk sounding even more redundant, I'm going to hit another issue you addressed by quoting whatever it was you quoted.
The issue: is it right to hack a network then turn around and help them fix the problem?
I'll draw a parrallel. Let's say you're sleeping peacefully in your house at night when somebody breaks into your garage, and into your ferrari, hot-wires it and goes driving around a little bit. Then they take it back the next morning and tell you all that they did to break in and help you prevent it happening again. Wouldn't you be just a little bit pissed? That's breaking and entering. That's tresspassing. That's illegal and can get you into a hotbed of trouble.
Likewise with a businesses' network.
Even if you left your door unlocked, it is tresspassing on private property if somebody were to just walk right in and sit themselves down looking as comfortable as you please. Ok, yeah, sure, you have the door unlocked, but that doesn't make it RIGHT that the person just walks in like it is his.
It's WRONG people. Admit it. Don't pretend. Just say "yeah, it's wrong, but I don't care". And face the frickin consequences of your actions.