Yes I agree with Zeffy, how would the touchdown have affected the truck tilt? These are not squat (compression) sensors, they are tilt sensors as I pointed out in post #53.
Provided the speedbrakes are armed, they will deploy as soon as the truck untilts, and this will happen once the gear touches the ground. If the speedbrake is not armed, or if it fails to deploy, then manual speedbrake would be necessary.
For a planned landing with automatic speedbrake inoperative and that is on on a dry runway at ISA, you would be looking at another 850 feet landing distance or a performance degradation equivalent to a mass increment of around 16,000kg. That still assumes that speedbrakes will be deployed manually after touchdown.
The reversers on the 757 can occaisionally be awkward to get through the lever interlock position, and the reverse levers may well be re-cycled in order to achieve the desired result. If one or both reversers are selected through to reverse idle, the speedbrakes (all 12 spoiler panels) will drive up irrespective of the lever position being armed or down.
In the normal course of events, the only time you wouldn't get spoilers after touchdown assuming no indication of "spoilers" or "auto speedbrake" on the EICAS / Discreet warning system prior to touchdown, would be if you selected or left the speedbrake lever in the "Down" position, didn't then deploy them manually after touchdown, and couldn't achieve reverse thrust.
That is not to imply that any of that happened in this incident, but simply to provide some information.