This may get me in trouble with some of you, but I feel the same way about handgun hunters and some bowhunters. Yeah, you can take game that way, but most people shouldn't. The trick isn't trying to kill an animal in the most challenging way. Use the best tool for the job and make the kill as humanely as possible. The trick should be in getting the animal to drop in a heap and not being a blood trail where the animal isn't found and left to die a slow death.
To quote Dirty Harry, "A man's got to know his limitations." If you aren't 100% sure of the shot, pass on it and wait for a better opportunity.
It was fortunate for that doe that HunterCO was in the right place at the right time. HunterCO, will you catch any grief for the mercy killing?