It is my opinion that they say that because the cast data is much lower than normal jacketed commercial bullets: it "covers their respective buttocks" if someone loads them hot.
Actually doing a complete "recommended" load data would be costly: they would have to ensure the loads are withing SAAMI pressures and so forth to prevent a lawsuit (that is the world we live in).
Just because I have some of those 125gr 9mm and pushing them as +P loads without issues doesn't mean X-reload would publish that data.