Even if Capt was incapacitated the F/O would be able to taxi off the runway at a highspeed exit with just the rudder pedals so blocked runway shouldnt come into it.
Airline SOPs do not allow this to happen , not even on the A320/1 where there is a tiller on the RH side . So the FO can land the plane but can't taxi the a/c after landing, this calls for a full stop on RWY and then radio for a tug