Bad news if you’re not an American: you will not be allowed to opt-out.
“Once the biometric exit program is a nationally-scaled, established program, foreign nationals will be required to biometrically confirm their exit from the United States at the final [boarding] point,” said CBP spokesperson Jennifer Gabris in an earlier email to TechCrunch. “This has been and is a Congressional mandate,” she said.
Fuck that shit, that's what international passports are for. Jesus, the US already has all of my fingerprints 3 times over, my social security number, they now need to know where and with whom you're staying for ESTA. Hell, they even know when, where and from which IP I booked my flight. Give it a few years and they will make the now-optional 'social media accounts and passwords' mandatory too.
There is no need for hackers, the US government literally already has everything to steal my identity already.