It was either Scott Clark or Carl Trueman that said this. I think the point is a profound one and it helps explain both the Reformers use of ancient sources even while noting significant disagreements with them. Someone had pointed out that the Reformed actually differ with Augustine on justification. Yes, and what of it? It actually illustrates how we use ancient sources. We are not cherry picking through the fathers, but reading them in conjunction with our reading of Scripture.
I grant that Augustine had a (from my perspective) a problematic view of justification, even if I can appreciate what he said about original sin and predestination. If I read Scripture and note that faith is contrary to a works-principle, and yet see elements of a works-principle in Augustine, then I politely say Augustine erred on this point. Even the most hard-core Anchorite does not agree with even his favorite fathers on everything. Even Athanasius taught the extra-calvinisticum (and this is extremely problematic if you believe what Leontius of Byzantium taught regarding enhypostasia).
A clearer example would be St Anselm. If it weren’t for St Anselm we would be stuck with some of the sillier ransom theories of the atonement. Do we fully accept what Anselm said? No, for few of us mentally operate in terms of feudal justice. But he asked the right questions.