Earlier quoted context omitted.
They're returning the rabbits to the previous owners. There's no further expectation of duty to either party.
The situation implies that the person selling the rabbits as pets would attempt to rehome them or care for them as pets. There's a difference between being technically correct, and being moral. While the language used is technically correct for the situation, omitting the information about where the rabbits end up is immoral. Clearly OP understands that if the whole truth was told, they wouldn't be getting a free sou…
No of course not, it's none of the seller's business. If they say "hey we're vegan please don't eat our rabbits" that's a different matter, it would be at the very least polite to respect those wishes.
Why on Earth would returning a rabbit to a farm where they eat them be any different? In this case the possibility is perfectly clear.