SAFE-T claims are for reimbursement after Amazon decides to refund a buyer. So this seems to mean that Amazon would refund the buyer first and then a seller files the SAFE-T claim. This may be necessary if the buyer returned the wrong item or it was damaged.
File a reimbursement (SAFE-T) claim
The Seller Assurance for e-Commerce Transactions (SAFE-T) process allows you to file a claim for reimbursement if you want to appeal Amazon’s decision to issue a refund to a customer. At Amazon’s sole discretion, you may be issued a reimbursement in cases where Amazon determines that you were not at fault.
Note: Orders against which you issued a refund to the customer are not eligible for reimbursements.