The question took Victor of guard. He had expected to make a purchase, but not actually drink.
On second thought, it made perfect sense. This test would screen out Arbiters. Any vampire refuses, they die. They accept, they're a new customer.
Victor considered the options before him. Not only would drinking it violate his oaths and the laws he protected, it would be doing the very thing he now hunted other vampires for.
But it wouldn't the first time. Victor knew the taste of human blood well. The sheer euphoria. And besides, he had no other choice. Right?