No doubt but that is an argument that would only have weight with a certain group of Catholics. To make an argument that has a chance of being compelling outside of that narrow context - one needs the scriptures. And that is what is needed in the context of "Christian Forums" areas that are not "Catholic only".
Our friend
@Xeno.of.athens was simply stating what the Roman Catholic Church believes.
However, I would argue that considering that the SDA also has a teaching magisterium in the writings of Ellen White which are officially regarded as inspired prophecy (and which in volume greatly exceed the two, and indeed there are only two*, infallible dogmatic definitions of the faith made by the Popes of the Roman Church since Papal Infallibility was made a dogma at the First Vatican Council), and considering for that matter that every denomination has its own particular distinctives, not only do I think the suggestion that Catholics not quote their internal documents in General Theology to be unfair to them, especially since Roman Catholics are among the many denominations which reject Sola Scriptura (which also include not just Orthodox churches, but Protestants and Restorationist churches, including high church Anglicans of the Anglo-Catholic school, Quakers, certain Pentecostals, and others, and indeed the historic Waldensians and Moravians did not preach Sola Scriptura, and furthermore the Lutheran, Anglican, Methodist and historic Calvinist interpretations of Sola Scriptura are very different from how others define it, in that supplemental material such as Patristic writings, the creeds, the liturgical texts and hymns, and theological works such as Calvin’s Institutes, and Barth’s Church Dogmatics, are extremely important. They are also particularly relevant to this discussion, which concerns the Reformed doctrine of Limited Atonement, along with other works of Reformed systematic theology.*
But beyond that, I would argue that discussions in General Theology are enriched by the quotation of material such as the Catechism of the Catholic Church, the Lutheran Book of Concord, the Anglican Book of Common Prayer, or indeed the writings of Ellen G. White, which personally I wish you would quote more, as I would find that extremely edifying, and as I have said, I give her a great deal of credit for ensuring that the SDA church embraced the Doctrine of the Trinity.
*I myself personally prefer Calvin’s Institutes, because he was clearly trying to follow the example of the Early Church and the consensus patrum, a phrase of Calvinist origin, even if some of the conclusions he drew, for example, concerning iconography, are erroneous.