I'd actually give score for killing the soldiers too, in fact, I'd give carnage bonuses, that gives an incentive to kill them and make the game harder for yourself.. of course, after going on a mad killing spree there would be too many soldiers to handle and you'd have to leg-it before more came, kill the sheep, burn the houses and get out.

This would add an extra addrenalin rush for those who want more excitement.. you could also level up your character quicker by killing the soldiers.. perhaps after killing a few soldiers, you get a bravery token to collect which boosts your stats temporarily making you more lethal. Kill enough soldiers and become Thor incarnate.

..but you can still only finish the level by killing the sheep