so, you want to use it for ferreting, which may involve it biting a rabbit, but if it bites YOU, it should be killed , surely, training/handling a kitt/ferret is the only way of teaching it what to bite, or not too,so the blame for a biting ferret would fall on YOU, and your failure to socialise the ferret, rather than the ferret itself
I use lurchers for rabbiting in general which "bite" rabbits and there is NO way would I tolerate a dog biting anyone,never had to do it yet but the first time a dog did would be the last, end of. Pray tell how you teach a ferret what to bite and what not