With flaps out of up, but not in landing position, activation of VNAV in VNAV PTH
changes the reference thrust limit to CRZ. However, pressing TO/GA changes the
reference thrust limit to GA and GA thrust is available.
Pushing either TO/GA switch activates a go-around. The mode remains active even
if the airplane touches down while executing the go-around.
When the flight director switches are off, pushing either TO/GA switch displays the
Flight Director Bars.
An automatic go-around cannot be initiated after touchdown.
Note:
An automatic go-around cannot be initiated after touchdown or if the aircraft
is below 5 ft radio altitude for more than 2 seconds.
Now I would have thought that the implication of that was that the auto throttles are closed and will not re-open.
It also would seem obvious that the automatic go-around functions if the autopilot is in or out, and/or the auto throttle is engaged/disengaged.
Why would you imagine that the auto throttle would try to maintain the selected speed during the ground roll?