Eller is not the judge. Her comment carries no weight. She just echoes Carnes' verdict. Under the circumstances I'm sure Carnes had the authority to set up a court wherever he deemed necessary. Curly would have been judged not guilty no matter where the trial took place. A technicality is not a miscarriage of justice.
Hammerstein's named his play Oklahoma!. It's not the same as Riggs' play.
Fish should have written or commissioned his own work if he felt so strongly about frontier justice. Instead he took a famous piece by an esteemed playwright like Hammerstein and totally distorted the original's intent for God knows what purpose.