Re: One crime.
It's not a "punishment" exactly, it's meant to be coercive. It's meant to last until either she gives in, or the reason for imposing it vanishes. The flip side is that since it's not a fixed sentence, she can end it any time she chooses.
Is it "fair"? Well, maybe not. But the word "subpoena" means "under penalty". The whole point is that if you don't comply with it, there's a price to pay for refusing.