I probably shouldn't give my two cents on this issue, but I don't recommend taking WC or releasing it or its offspring. The main reason is that it may spread diseases to the wild population. But now that you mention it, it probably would be more likely to become prey, once it has gotten used to the safety of the terrarium. Foreign diseases are a bigger concern though, since it affects more than just that one snake.

There are also other potential risks, including the snake "getting lost", which I understand is something that has been documented in relocated snakes here in this country. Apparently they follow a particular circular route every year, from the den to where they spend the summer and they eventually end up back at the same den in the autumn. I actually read through an article on the subject a couple of weeks ago, although I didn't have the chance to copy it. I understand garters behave in much the same way. Anyway, relocated snakes appear to have problems figuring out where the hell they are. Of course it's a bigger problem here, since good dens are further apart.