God uses allegory and metaphor to teach with in His Word. So any Christian who doesn't understand how that works and deems it as speculation shows they have missed another level of God's teaching in His Word. Those allegories and metaphors are not speculation, they are tools. Our Heavenly Father uses them to make it easier to understand, not more difficult. But the Bible student must first pay attention to them.
The below is an allegory, not speculation. God uses the title of the king of Tyrus (ancient Tyre), but that's not really who He is pointing this to...
Ezek 28:11-19
11 Moreover the word of the LORD came unto me, saying,
12 Son of man, take up a lamentation upon the king of Tyrus, and say unto him, "Thus saith the Lord GOD; Thou sealest up the sum, full of wisdom, and perfect in beauty.
13 Thou hast been in Eden the garden of God; every precious stone was thy covering, the sardius, topaz, and the diamond, the beryl, the onyx, and the jasper, the sapphire, the emerald, and the carbuncle, and gold: the workmanship of thy tabrets and of thy pipes was prepared in thee in the day that thou wast created.
14 Thou art the anointed cherub that covereth; and I have set thee so: thou wast upon the holy mountain of God; thou hast walked up and down in the midst of the stones of fire.
15 Thou wast perfect in thy ways from the day that thou wast created, till iniquity was found in thee.
16 By the multitude of thy merchandise they have filled the midst of thee with violence, and thou hast sinned: therefore I will cast thee as profane out of the mountain of God: and I will destroy thee, O covering cherub, from the midst of the stones of fire.
17 Thine heart was lifted up because of thy beauty, thou hast corrupted thy wisdom by reason of thy brightness: I will cast thee to the ground, I will lay thee before kings, that they may behold thee.
Those statements in red should immediately get the attention of the true Christian Bible student. When was the flesh historical king of Tyrus ever in God's Garden of Eden? He never was, but Satan was. Whenever was the king of Tyrus 'an anointed cherub that covereth"? The flesh king of Tyrus never was, but that is what Satan was before he rebelled in the time of old. The stones of fire refer to God's Altar in Heaven, the flesh king of Tyrus never was at that Altar.
So is God speaking of the flesh king of Tyrus like verse 12 states, or is He using allegory talking about Satan?
Even some Bible scholars tread too carefully with that allegory about Satan, and are afraid to mention that it might point to Satan. They will instead 'speculate', and compare all that to the flesh king of Tyre of how he exalted himself like God, doing those things. But comparing the flesh king to a cherub guarding the Mercy Seat that was in God's Garden of Eden is speculating too far when thinking that's about some flesh king.
Ezek.28:18 Thou hast defiled thy sanctuaries by the multitude of thine iniquities, by the iniquity of thy traffick; therefore will I bring forth a fire from the midst of thee, it shall devour thee, and I will bring thee to ashes upon the earth in the sight of all them that behold thee.
19 All they that know thee among the people shall be astonished at thee: thou shalt be a terror, and never shalt thou be any more.
KJV
The above shows God has already judged and sentenced that one to the future lake of fire. What flesh man today has already been judged and sentenced to perdition into the future "lake of fire" at the end of Revelation 20? NO... flesh man has, not as of yet. Not even Judas Iscariot has been judged and sentenced yet! But Satan and his angels already have. Is that 'speculation' then? No, of course not. It is understanding our Heavenly Father in His Word. Just because someone doesn't see that yet doesn't mean it is speculation.
You should look at the Ezekiel 31 allegory, it's even more telling, for those given to understand it. And the allegory in Isaiah 14 about Satan is also easy.