We can't really say it was a perfect crime without knowing what kind of crime it was supposed to be all along. If this was supposed to be a robbery, for example, it is not perfect as nothing was stolen (that we know of). It does seem Clint interrupted or altered something that was happening. But we do not know exactly what this is.
Myself I think that gaining access to the inside of the house was part of the original crime. If this were purely a kidnapping why wait around the house 10-15 minutes, going in and out of the garage, etc. Just snatch Holly and run. And since Clint heard voices outside the house before he saw the figures in the garage, Holly and the suspect seeminly went into/back into that area after being outside. I do not think the suspect knew Clint was home then. I think the dog barking and Clint peering into the garage tipped him off and then he made a hasty retreat from the property with Holly in tow.
Now why was he there? Was this some sort of sexual assault/infatuation crime where the suspect wanted to do whatever at the home or in the home, thinking it was just him and Holly? I sort of think this was the intent partly because it seems Holly and the suspect entered back into the garage after they were outside the house initially.
In an unrelated thought train... the lack of a visible weapon has got me thinking a bit. This is just random stuff/details.... Being hunting season, etc. and with the suspect (and seemingly lots of folks) going around in camouflage you would think perhaps the suspect would have had a rifle. It would not be unusual, uncommon or terribly suspicious. And if you were going to commit some sort of crime a rifle is a good weapon of choice. At least if you were observed going to and from the scene with a hunting rifle no one would be obviously alarmed. I suppose a kife or pistol would be easy to conceal. I know some hunters carry pistols as a back up, but this was not a hunter. Since Clint never mentioned seeing a large, obvious hunting type weapon, the suspect most likely did have something small like a knife or pistol.
It most definately was a perfect crime in the sense that Holly was abducted without a trace never to be seen again with not a clue to go on. Now, I wouldn't argue if someone said it was unintentionally perfect, but none the less it couldn't have gotten anymore perfect as far as how the abduction went.