Modalism was condemned by a church that was, at that moment, developing the doctrine it later called orthodox. Condemnation by the winning side isn’t evidence the losing side was wrong.

True in itself: a condemnation is a historical fact about what the church decided, not a proof. The claim here is precisely historical, that the analogy restates a position the church examined and rejected, and the condemnation shows that. Whether the church was right to reject modalism is argued from Scripture elsewhere in this case, where the reason given is that modalism cannot account for the Father and Son speaking to and sending one another. The condemnation records the verdict; the texts give the grounds.