Actually it appears (notice I said appears) that Kevin and Jodi are the only ones being truthful. They have nothing to gain by saying what they are but J&K have everything to lose if they tell the truth. Your forgetting too that they both said they have talked with J&K concerning the children but that J&K said it's their life, this is how they're going to provide for the kids.
Interesting that Kevin & Jodi are scum but J&K are fine even though they are exploiting their kids, showing private moments (ie: potty episodes and vomit) for the world to see, writing books to capitalize on the cuteness of their kids, fighting around the kids, broadcasting to the world that their marriage is in shambles which the kids will be able to watch on DVD and so on.

Sorry but all of THAT is much more damaging and "scummy" than what Kevin and Jodi did trying to help. Serioulsy, we all have seen how strong-willed and controlling Kate can be, do you think that she would listen to Kevin & Jodi? My guess would be no. Maybe by doing it so publicly it will work.