"React: After Antoine enters play, search your discard pile for an action card that starts a job and put it into your hand. Discard a card. You may unboot your The Sloane Gang dude at home and give them 2 bounty."
"Card effects cannot cause cards to leave your discard pile, and cards in your discard pile cannot be played.
During Sundown, discard all cards in your hand."
In reference to Compendium p. 11
When a card effect allows you to search for a card, you are not obliged to choose any that you find. You simply declare that you are not retrieving a card, and continue play. After you search your deck, you are required to shuffle it. If your deck has no cards (for example, they're in your discard pile instead), and you attempt to search your deck, the search immediately fails, and you do not shuffle your discard pile back into your deck.
If you are running Lacy or don't have a Job in your Discard pile, in either case, Antoine is played. You then Discard a card and you may unboot your The Sloane Gang dude at home and give them 2 bounty.
EDIT: This is a rules reversal from what was previously posted.