Anthony Buzzard is a leading defender of Socinian Christology/"Biblical" Unitarianism. He has made many embarrassingly bad arguments (1) against Mormonism and (2) in defense of his Socinian Christology, including his rather deceptive use of Bacon's 1902 article in Hebrews 1/Psalm 102.
He just posted a video where he argues that the Latter-day Saint acceptance of books beyond the biblical texts is what is in view in the pericope:
Don't mess with the book of Revelation! Mormons, Protestants.
To see why Buzzard is wrong, see the exegesis of Rev 22:18-19 provided in my book-length critique of Sola Scriptura:
Not By Scripture Alone: A Latter-day Saint Refutation of Sola Scriptura