Is it safe if the neutral lead is exposed and disconnected?
No.  In this condition, the exposed plug blade will be deadly. 

Every load connects hot to neutral.  It does so through some level of impedance, but that impedance is not enough to protect you from shock.

If you have a GFCI/RCD device somewhere protecting this load, that will intervene to prevent injury in this case. 

One detail: Current wants to return to source, not ground. For man-made mains current, source is the supply transformer, and hot power is seeking neutral.   It will be happy with ground, because back in the main service panel there is a neutral-ground equipotential bond connecting them, so it will go via ground to get back to neutral.