Nope they don't have to repo it, and I do not know why, since they will still get the same amount of money from you.

When they repo it, they sell it, after they sell it, you will have to pay the difference. so not sure why you are happy for the repo, the sooner they repo, they sooner they sue you, and the sooner they can start a garnishment on your pay, and so on. for the balance of the money