Because quite simply at the time maybe they believed it? Saying that they have never been exact with times anyhow.
MOO
Yes, and what's strange about this is that they were giving a time : 9:00 a.m. ,and a location,: by his classroom door. We simply don't know if it was a child or an adult who saw him. However... : what if this 9 :00 o'clock witness actually saw Kyron by his classroom door with TH ? What if they were seen together going towards the exit door by this witness ? IIRC, LE has never said who,if anyone,was with Kyron at that time.
Now,that's reason enough for LE to keep this witness under wraps ... Speculative,but interesting,and MOO.....
All JMO