What good reason?
We keep being told that man is the problem with species going extinct. But that is not true. We have no shortage of pigs, cows, dogs, cats, goats, hamsters, etc. All these animals are close to man and are cared for by man. The animals that are in danger of extinction are the animals that man is forbidden by the state from nurturing.
Mostly having to do with humane treatment, but also having to do with elementary safety.
1. It's generally bad for the health of the animal in question. Not this time, perhaps, but generally, because most people don't know how to take care of the needs of a wild animal.
2. Wild animals are ... well, they're wild, and thus can be unpredictable. For some species, there's real danger in having wild animals living among humans. Even for deer (older than fawns), they could cause injury.
3. Possibility of disease: if the animal escapes back into the wild, it could take diseases with it. Similarly, bringing a wild animal in among domesticated animals could bring disease into the domesticated population. As an example, brucellosis could be spread in either direction.
There are more examples, but I think you get the point.
I don’t know about where you live. But here in South Carolina, deer are a real menace. They are everywhere.
Every week I see two or three more deer lying beside the road killed by cars and trucks.
There has been discussion of putting birth control chemicals in deer corn to try and control the herd.
It’s a real problem here.