The only way i know which would get the Ground spoilers to deploy in the air would be if you are using the Flight spoilers in the AIR and you have an Ground/Air logic failure..example you take off and the gear will not move up after take off..you retract the flaps and the config horn still sounds...then you are in trouble
including that you MUST NOT use the speed brakes in flight until you have actually landed....hope that helps...
And to answer the initial question..i think boeing doesnt want you to arm the speedbrakes for Landing as by having the speedbrake in down detent it will DISARM the autobrakes system...i dont think any of us would like a fault in the antiskid system to malfunction by giving unwilling inputs to random wheels as you touchdown(wheels spinning)..could be interesting...
After landing if needed using manual braking is possible as it reduces your stopping distance which also is an alternative way to disarm the antiskid..
