"Glorious appearing" is not a proper translation. The true grammatical translation and transliteration, word for word, is "The appearing of the glory of the great God and Savior of us Jesus Christ."Here is the passage. The phrase bolded in verse 13 is shown to apply just to one person. Himself is singular. So “the great God and our Saviour“ applies only to Jesus Christ, so Christ is called “the great God”.
13 Looking for that blessed hope, and the glorious appearing of the great God and our Saviour Jesus Christ;
14 Who gave himself for us, that he might redeem us from all iniquity, and purify unto himself a peculiar people, zealous of good works. - Titus 2:13-14
Nowhere else in scripture is the "appearing of the glory of Jesus Christ" substitutable with the appearing of Jesus Christ himself. This tends to rule out the Trinitarian rendition as much on theological grounds, as on grammatical grounds.