The related point is made by matt13weedhacker, in a reasonably coherent blog page.
1 John 5:7-8 Comma Johanneum – 1 John 5:6 Vulgate Variant: “Christus est veritas”
“Christus est veritas”
these (Codex’s Ottobonianus and Montfortinaus) are the only two Greek copies of the NT known to exist that have Jerome’s signature: “Christus est veritas” translated into: ὁ Χριστός ἐστιν ἡ ἀλήθεια or ὁ Χριστός ἐστιν ἀλήθεια.
The straw man element is that any of these evidences should have a "a pure Greek heritage and lineage", since the restoration of the verse largely was based on the Lateran Council. Matt tries to pretend that otherwise they are "simply corruptions" circular, blah blah.