Kairos' grip on the beam tightened several times over. His mind went into overtime as he calculated how fast he would have to run to get to the exit before Sara did. From his judgment, if he ran as fast as possible, then he should be able to make it through the exit before she did.
In other words, he had to make the decision right now.
Countless different thoughts rushed through his head at the same time. At its culmination, it all came down to one thing.
It was a hallucination.
He found that the timing made too little sense. The actual chances of the timing being so tight at his full speed were just too coincidental. However, he came to the decision to move.
Because if it really was wrong, then he could just use his future sight to check.