Yes, there was. It was one of many "reasons" that cropped up in the tabloid wars, along with:

• disagreements over money,
• Jon belittling Richie,
• Dorothea wanting Richie off the tour because he partied too hard and was a bad influence,
• Richie being cut loose because his substance abuse created so many problems for the band,
• Jon holding Richie back creatively,
• Richie wanting to focus on NikkiRich,

and others I can't recall right now.

All of them were based on "information" received from "sources", so most of the time they were treated with the same liberal skepticism they deserved. I think the only times people really put any stock into any of them were in cases where a particular "reason" coincided with their own previously held assumptions about what happened.

For what it's worth, I personally believe that if Jon actually said those words, it would have been in a tongue-in-cheek, or even self-deprecating way. I could be wrong, but I would hope that neither of them would seriously use the other's child to win a point in an argument. JMO