Also, on a CAT3 No DH approach there will be no "50 above" call/autocall (or 100 above for that matter). So by the time the F/O notices the Capt is incapacitated the aircraft has landed itself! Just select reverse, disconnect the A/P, override autobrake as appropriate and ask ATC for assistance and medical as required. A G/A would really screw up the Captains chance of survival and increase the F/Os workload tenfold.