Just thought you should see this:
"Auctions in Re-Tail, TBT Marketplace, and Villager Trading Plaza
When hosting an auction for your items or moving villagers, you must follow through with the sale unless you explicitly stated that the auction results are subject to be changed. Otherwise, the auction winner may give the host negative feedback for failing to complete the sale. The auction winner may also receive negative feedback if he or she fails to follow through with the purchase. Include as many rules with your auction as you feel fit, such as starting bid price, time limit, and bidding increments." It's in the rules that you can sell moving villagers.