The point is that it is NOT clearly a description of Christ's second coming.
Consider this text from Daniel which was well known to Jesus' contemporaries:
“I kept looking in the night visions,
And behold, with the clouds of heaven
One like a Son of Man was coming,
And He came up to the Ancient of Days
And was presented before Him.
14 “And to Him was given dominion,
Glory and [k]a kingdom,
That all the peoples, nations and men of every [l]language
Might serve Him.
His dominion is an everlasting dominion
Which will not pass away;
And His kingdom is one
Which will not be destroyed.
Is the "coming" of the Son of Man (clearly Jesus) a downward return, as in the second coming?
No. It is an upward ascent of vindication after defeating the beasts - clearly descriptive of Jesus' victory at the cross and attendant installation as Lord of all creation.
So, as we see, there is a powerful argument that texts that refer to Jesus's "coming" may refer to his coming up to heaven after His victory at the cross - something that has already happened - and not a downward "second coming".