What a dick, though..
This does not imply that helping law enforcement is always ethical. In this case, helping law enforcement take down these criminals is not a "dick move".
Come on man.
Note: there is a lot of grey in the world, but intentionally targeting the innocent is black & white.
There is also the question of who's version of innocent you use, for example if my moral/ethic system says X is a terrible offense and your system says X is just OK, which is most applicable to the classification of innocent? (for a simple concrete instance of this, look at the global variations of views on homosexuality, ranging from "it's nothing we should care about societally" to "we should care and embrace" to "it is a death penalty offense" -- not making any statements here on the debate, that is tangential to this). The situation needs to be looked at with an eye towards intent as well as just questions of innocence.
He broke a trust barrier. He is just as guilty as the peers he just sold out.
Now what? He just sits back and kicks it good while his friends get canned?
Clearly, you would let your friends take a fall for you when you're just as guilty.