OK, so it's illegal, but there's nothing to stop passengers from signing a waiver.
It's not as if it's forced deportation - people appear to either want or need to travel to the USA and they're free to decide whether they're prepared to provide their data to a range of paranoid and/or vindictive government bodies.
Don't get me wrong - I think the parochial agressive attitude that one encounters athe border stinks, but the decision's with the traveller.
The neighbourhood (which unfortunately encompasses the globe) bully doesn't give a toss.