I think I agree with Bec. At the point it becomes libelous (it is in print, after all) a quick letter from your attorney to the program *owner* (which in this case I think is probably different from the person making the comments) will probably solve the problem.

Or, an alternative approach might be a phonecall to the program owner, sort of a friendly "Um, I don't know what problem your guy has with us, but we don't want to be enemies with anyone, can we talk about it?"

Unless the program making the insults has more money than God, they'd be idiots to be doing shit like that to a larger progarm that has a lot of $. You sufficiently piss off a large program owner and even if it isn't economically feasible, the program owner could get mad enough to be willing to drop a hundred grand just to make a point and make life hell for the guy saying the shit.