You gave two reasons: 1). Jesus said it and 2). It's different. Number two is begging the question and number one has no rational basis for it to be a reason for exception.

If you're not willing to consider direct quotations of Jesus legitimate, on what basis do you consider any of scripture legitimate? As for the rest, here's your original post:

"It's always interesting to me that the Bible, as understood by atheists, is a garbled via centuries of telephone game, mistranslated and full of scribal errors, ex post facto prophecies, and unlikely to have accurately captured or communicate anything of substance... Except for this one prophecy, which apparently is the only statement ever recorded by Jesus to be worrying down by eyewitnesses. Curious."

The reasoning presented here is that atheists allege the content of the Bible is unreliable in terms of authenticity, except where a particular part of it benefits their argument.

This reasoning is invalid because it ignores that the parts atheists commonly allege to be distorted are of a fundamentally different type than what's being discussed. We are discussing prophecies. Ex post facto, the vague horoscopey type that can fit any era, and the third type, vastly less numerous than the other two, predicted by Jesus, concerning the timeframe within which to expect his return.

Partially. The Kingdom of God is inaugurated at the resurrection. Te destruction of Jerusalem is the sign of God's Kingdom. The judgement comes at Jesus' return, and is unrelated (in sequence) to the other two. You're conflating events when there is no reason to do so.

This is wild. You're telling me this part:

"For the Son of Man is going to come in his Father’s glory with his angels, and then he will reward each person according to what they have done. Truly I tell you, some who are standing here will not taste death before they see the Son of Man coming in his kingdom.”

...takes place thousands of years after the rest? Does the way the verse is written suggest that to you?

Again, the past twenty years of scholarship are against you on this point. The gospels present Jesus as divine but the revelation of Jesus' status comes only after the resurrection.

You've not yet supplied any citation for that claim, and I've supplied a verse wherein Jesus, well before his crucifixion, asserts that those who do not believe he is God will die in their sins.