You mean, besides his family, friends, and loved ones when he loses his job and potentially ends up in prison. You're underestimating the amount of training and internal oversight that occurs.
The cases of caught individuals seem to have gone under-punished, as they sound worthy of prison time.
Also, even if the NSA polices against personal abuses, why would it police against systematic abuse for government's purposes against the constitution?
Self-policing does not work well, especially without elaborate mechanisms to enable it to work, and especially with a combination of secrecy and lack of oversight.
Now, systemic problems are a different issue. But the article we're all talking about here is written by an analyst from his own perspective.