Aside from guarding even more loot, the Ogre Commander has a 500 gold bounty and is one way to complete a quest that gives +10 experience(level 2 get?) and unlocks the refugee camp. It also drops a very strong(by early/mid game standards) DEF-boosting monster material for either Aura or her future slime partner. Using the collar to get an early kill on the Ogre commander can be viable as an alternative to taking a few lewd options for gold if you're trying to protect Aura's innocence(and your victory score). Especially if you know fire(since this lets you skip combat when harvesting the star metal in the refugee camp).
The collar will also reset Aura's hp/mp so you can get more done on your day 1(or day 2/3).