If the USSC reverses, will Phelps then be held liable to reimburse this?
They could certainly do so for the fees incurred in the USSC appeal. I don't see the Supremes taking this up as the appellate decision was clearly correct on the merits.
It won't be reversed. The Phelps know what they're doing and they're good at it.
Someday these folks are going to mess with someone who has nothing to lose and this will be a very bad day for the Phelps family. And when this day comes, I'll feel not an ounce of sorrow for these despicable people.