it depends on what they had permission for.
I am not familiar with that case or with what happened there, but if I understand correctly, there was a "contest" to hack a system, so there was a permission to do that.
Now back to my question:
I make a contest: See how cool my security systems are! I invite you all to try to get past my security system into my house.
You come and successfully enter my house. You can argue, yes, I gave you permission to enter. So it is not trespass.
But did I give you permission to tell everyone where in the house I have my dirty laundry? Did I give you permission to tell everyone how you got in there?
To answer that you would need to know: the details of the agreement between me and you. If the agreement did not cover those areas, you would have to look at the law: is there any law that says this is wrong? What about privacy for example?
Then you argue.