aahh...
But if the flaps would not extend because of high speed, that means that they were kept at 15 by flap load relief. If that were the case, the flaps would extend to the selected setting during the landing roll as the plane was decelerating.
They did not.
Therefore, the flap lever was in 15, and the flaps stayed there. Apparently the crew did not have time/forgot to select flaps 30.
And that would be OK (sort of) if they simply had made a go-around.