Was my husband rightfully fired?

My husband works for a large corporation as a craft employee. Last week on the job he was using a box cutter. While using the box cutter the razer shattered and a piece hit him in the eye. At the time of the incident his supervisor was standing right next to him. He asked my husband if he was okay, and my husband thought he would be fine. He knew his eye was scratched, but thought he could deal with it. The supervisor didn't want him to make a workman's comp. claim. However, that night my husband was in such severe pain he couldn't even sleep that night. That morning, first thing, he called into work and filed a claim. He then went to the doctor and was supervised by one of the safety workers in the doctor's office. At the doctor's office he was told that he was not allowed to go to work the following day. The safety worker then asked the doctor to change his note to being able to go back for light work. My husband was going on vacation that day anyway--and wouldn't be going into work. The safety worker said if the doctor didn't write his note that way the corporation would lose their 15 years no lost time incidences record, and he would possibly lose his job. The doctor obliged. After vacation my husband went back to work, and they terminated him. They considered him too much of a safety liability. My husband has been working for this corporation for over 4 years with out any safety violations--no write ups. Was he rightfully fired, or do we have some kind of case?