>>213298103
Because he knew that for Gohan to unlock his hidden potential and defeat Cell he'd have to fight him at full power, as fighting a weakened Cell would result in no further growth for Gohan as he'd either just stomp a tired Cell or Cell would get completely serious and murder him in desperation (because Perfect Cell was still massively stronger than MSSJ Goku/Gohan)

>>213298366
There is no reason for this, this was a callback to sparing Frieza with absolutely none of the rationale or characterization because Toyo's a complete fucking mark and terrible writer.