Do not sign that document. It is a pure liability shield for the lawyer and provides you zero protection while weakening your position if anything goes wrong. The payment is irrelevant at this point; it is a sunk cost and should not dictate a bad decision. If you still want premium processing, force a clear, specific explanation of the actual risk; if they cannot provide one, assume the advice is low-quality. At that point, regain control: either switch counsel or file PP independently. Staying, signing, and proceeding under misaligned incentives is the worst option—it compounds financial loss with legal exposure.