While this is unexpected, I don't think it's too far-fetched. You got your typical rats who take the stand to snitch on anything and anyone just to save their ass from getting thrown in jail, but you also have the kind of informants that - from their point of view - are using law enforcement to stay on top. They sporadically sell out a few semi-rivals or some lower level crooks they deem less competent all the while continuing their own criminal activities. The information they give is enough to keep LE happy and it isn't going to crush their own organization. In their mind they're playing LE to their advantage and their own criminal careers continue to prosper. Stuff like this is actually very commonplace in a lot of European underworlds; traditionally you always had and continue to have upper echelon gangsters in places like London, Amsterdam, Glasgow, Liverpool, Dublin, Paris, Marseille, etc...who were/are in various degrees known to be registered informants. I don't think it's all that surprising this happens in the USA as well. And make no mistake about it, these are top-level criminals that are feared. They have/had carte blanche for years and years and years. And basically nobody in the underworld who might be aware of any of this is going to call them out for being a "rat" just because of how shrewd and outright terrifying these people are. For them playing the law is just another racket just like their involvement in extortion, infiltration, drugs or shylocking is. It's another swindle in a dog-eat-dog game.

I get the "a rat is a rat" saying, but some are playing the game a bit different - and possibly a bit better - than the others.