It's not really fair to claim that Lamo was wrong to turn Manning in based on retrospection like this.
It would have been entirely reasonable at the time to assume that some of the 260k+ cables might have endangered US soldiers, allies, and others. The fact that we can't prove it did now does not change the reasonableness of that conclusion nearly a decade ago, and given the stakes at play it seems unfair to vilify someone for doing what he did.
- https://www.buzzfeed.com/jasonleopold/secret-government-repo...
> Regarding the hundreds of thousands of Iraq-related military documents and State Department cables provided by the Army private Chelsea Manning, the report assessed “with high confidence that disclosure of the Iraq data set will have no direct personal impact on current and former U.S. leadership in Iraq.”
- http://www.politifact.com/truth-o-meter/statements/2017/feb/...
> In the several years since WikiLeaks released hundreds of thousands of government documents leaked by Manning, the government has not publicly identified a single example of the Taliban killing someone because that person was named in the leaks. If someone had died as a result, it seems logical that the incident would have become public knowledge, either through Manning's trial or in media reports.