Really, Brakelite? You would resort to special pleading just to force your fictional story onto a lament that was clearly addressed to the king?
Show me anywhere in the NT where Ezekiel 28 is quoted in relation to your fallen angel? Just one reference? How about anything even remotely close? Can you do that?
The prophecy was given, and it was fulfilled, just like the chapter before it concerning the city of Tyre. And for the record, Ezek 27 has nothing to do with your imagined judgment on the what you call the underworld!
You know what’s ironic, Brakelite? The truth has been taught to you all along, if only you would pay attention!
“Page 536” of your Seventh-day Adventists Answers & Questions on Doctrine
THE WICKED WILL BE CUT OFF. This thought is emphasized repeatedly, especially in the Old Testament. The psalmist, looking forward to the time when sin would be abolished, declares, "Evildoers shall be cut off" (Ps. 37:9); and again, "The wicked are cut off" (verse 34). The words "cut off" are, in the main, rendered from the Hebrew word karath. This is a strong word, and is several times translated "destroy," as in Ezekiel 28:16.
Ezekiel 28:16 "In the abundance of your (King) trade you were filled with violence, and you sinned (only humans can sin Romans 6:23); so I cast you as a profane thing from the mountain of God, and I have destroyed you, O guardian cherub, from the midst of the stones of fire."
He did become wicked though but did not start that way! - only humans can become evil Brakelite! Angels possess God's Divine Nature and therefore are Pure Holy Beings who always do His Pleasure.
The Context of the chapter is that Tyre held a privileged position in its relationship with Israel. David and Hiram maintained close ties (2 Sam. 5:11; 1 Kings 5:1, 6–7, 10), and Hiram and Solomon formed an alliance in which Hiram supplied materials for the construction of the temple (1 Kings 5:12, 17–18). The language of Ezekiel 28:13–18 draws on Israelite worship imagery and is used symbolically to describe the relationship between Israel and Tyre, implicitly highlighting the divine favor that rested on Tyre due to its association with Israel.
The King lost God's favor and received His Wrath.
Will future Kings receive the same just judgements as Nebuchadnezzar in Isaiah 14 and the King of Tyre in Ezekiel 28?
Yes!
And before you get too carried away with the “guardian cherub” idea, cherubim were made of beaten gold and placed at either end of the mercy seat (Exod. 37:7–9), their wings overshadowing it as a single piece (Exod. 25:19–20). Though the Hebrew is difficult to translate, following the A.V., Tyre, as a major mercantile power, could be seen as privileged to “spread its wings” over Israel. It was the abuse of this exalted position that led to Tyre’s downfall (Ezek. 28:4–5).
Don't pollute God's beautiful imagery with your mythological nonsense!