a breaking story would name names...him not naming names just means he can use this as a hammer to get better terms for Techcrunch(either I get exclusive to every deal you guys do...or your names will be posted)
Arrington did the right thing. It's not about whether he caught a criminal, it's about whether he prevented someone from becoming one.
I doubt that they will abandon their ethical choice; they'll find smarter ways to do what they'd intended all along.
One thing that might work is if someone in the group has damning correspondence, everyone will panic and promise to "never talk about that summer again," genuinely preventing future problems.
Either way he loses that/those source/s for future stories. He did the only thing he could do, besides staying silent. If it happened to be the right thing as well, so much the better.
more likely is that he doesn't want anyone to get in trouble, he's just putting them on notice.