What if it was something else? You are aware that respiratory issues can be the sign of more serious illnesses right? The animal could have also died of a completely unrelated issue as well.With the clear signs of a RI, I don't see the point.
A necropsy give peace of mind regardless of the animal's price tag, I know that if I had a newly acquired animal die, I would want to know the cause.
Unless a necropsy is done everything else is just speculations and won't bring a definite answer.