Max N1 is max N1, whether it's the A/T moving the thrust levers or the pilot. The EECs are the things that give you max thrust and will prevent you over-boosting (thrusting) the engines, not the A/T, so your statement does not make sense.
Jeez,we are talking as you go around,thrust in auto mode,thrust is at max,then you say why not disconnect...
Im telling you unless you wanna keep on changing the thrust (manually)to achieve a continuous max thrust,then let the AT engaged.
The AT COMPUTER is using eec and adirus info to advance the thrust LEVERS to their optimum max thrust.
And by the way overboosting max N1 as you say is possible with the EEC,with the AT OFF.
The EEC has only an extra protection to avoid n2 overSPEED,not N1,via an overspeed governor.
In that case eec will command the fmv to reduce fuel to engine hence reducing n2.