Scriptura was still in the process of being defined at the time of these early writings.
To be honest, I am less impressed with the quotations in the first half of the article than from those from Athanagoras through the conclusion precisely because some come from writings that were deliberately excluded from the canon of scripture.
Even some of the latter sources come from questionable characters. Tertullian was declared a heretic; and certainly his self-castration is evidence that he was a fanatic. Hippolytus' dubious position is properly noted, although it is worth noting that a Eucharistic Canon attributed to him is found in all Western liturgies (as Prayer II in the Roman Missal, Prayer IV in the Lutheran Book of Worship, and Rite Two form B in the 1979 Book of Common Prayer.
I am most impressed by the quotation from +Cyprian, for here is a worthy teacher respected by both East and West.
However, there is also a quote from St. Clement whose credibility has NEVER been questioned as far as I know.
Scripture alone, but Scripture is never alone.