Underfire, the FMC speed coding to 240 its below FL 100 is nothing to do with ATC, its a VNAV coding to allow deceleration. :
Normally, the target speed is economy speed above the airspeed restriction altitude and 240 knots below that altitude, until deceleration for approach. VNAV will not permit descent below the airspeed restriction altitude until the airspeed is at or below the restricted value plus ten knots. The start and end of the airport speed restriction deceleration segment is shown on the map as a green open circles with no labels.
12-11.31.24 B-737NG Operations Manual Part B 38/26 SEP 13 Volume 5