Because being able to call someone a terrorist (or a hacker, in 5-10 years time) as a reason to turn off their credit card when it's the only method of payment left will be a dystopian nightmare.
But this is a contrived and frankly ridiculous premise.
Situations like this are why we have an independent judicial system. And even if we didn't who is thinking that credit cards are the only way to buy things ?
Yeah, tell that to the guy who wrote "ISIS beer fund" on his PayPal transfer to his mate that we have an "independent judicial system".
No - we have an outsourced judicial system, where Facebook and Google will spy on you more than the USGov, the bank will control your money more than the Government, and the insurance company will have you in an autonomous car faster than a mandate will. That's modern neoliberalism.
Situations like this are why we have an independent judicial system. And even if we didn't who is thinking that credit cards are the only way to buy things ?