I don't get it. What does Finalize Early do?
Releases funds from escrow (SR provides this for all transactions at no cost). When the buyer pays, he pays a Silk Road account, not the seller directly. Silk Road then notifies the seller the buyer has sent funds. When the buyer confirms he's received what he ordered (when the order's "finalized," rather), escrow funds are released to the seller. If the buyer claims the product hasn't arrived after x days, they enter an arbitration process with SR staff.
Finalizing early effectively bypasses escrow altogether and sends funds immediately to the seller before the buyer confirms receipt of goods purchased.