They could resurrect the tigers, but no billionaire would hunt anything so twentieth-century. They need prey as unique and post-natural as they believe themselves to be. You understand them well, and, therefore, can provide them with exactly that. You design and build bespoke animals: fleeting unicorns, fiery dragons, winged serpents, and other things --- beautiful, glorious things that will never be named. They pay you well.
Nobody pays you to build the tiny bacteria that will kill, in deceptive ways and after a time, any human who touches the carcasses.
They have their hunting, and you have yours.