Some snakes have scar tissue (usually from noserubbing or chronic RI) that impedes the nasal passages after the injury/illness is gone. If this is the case then you should have no problems introducing your snake to the rest of your animals.
The problem lies where it is still uncertain why the animal is wheezing. It is encouraging that your rainbow is otherwise doing well. Unfortunately there is a big gap in reptilian disease knowledge and a unknown viral pathology that chronically affects snakes as "poor-doers" is not all that far fetched.
Whenever introducing an animal to your collection there is some amount of risk. A lengthy quarantine time where visual healthy behavior is observed minimizes this risk.
What did your veterinarian say? Without knowing your experience, it is quite possible that your snake has chronic upper respiratory disease or pneumonia and you don't know it.
I hope my post gives you something to ponder,
Ian