You have complained about this, yet you took him hunting. So I would assume, that overall you feel positive about the guys character. Now the decision is really yours and you have to determine in your heartwhether this guy is worth further guidance or not.

Could it be that he was excited and under internal pressure to validate himself as a hunter or down deep is he wreckless and disrespectful of the critter. The one thing I don't like is that he wanted to give up on the blood trail (as long as you as the experienced hunter were maintaining a good attitude during the original process).

I think if this is a good guy down deep then the loss of the deer is minimal. If not, then perhaps it was your error in taking him in the first place. If you were unsure about him, but wanted to give him a chance, then good for you. Now it's your turn to decide if you want to help someone who could be worthy or solidify your feelings of apprehension and leave a bad taste in both your mouths.