He didn't slander. He took issue with some of Rose's facts, then asked Rose to respond. Rose did, with a threatened lawsuit.
And of course, there's always the chance that this particular priest was acting under orders or at least tacit approval
Oh. So smearing someone is OK, but slander is not?
BTW, Ninenot notes that the rector of Louvain who questioned Rose has just been hired by Abp. Dolan of Milwaukee in his diocese.
That doesn't surprise me at all.