My response:
Your son is entitled to Worker's Compensation coverage from his employer. In this instance, your son was working at the time of the accident - - therefore, coverage attaches. Worker's Compensation is a form of "No-Fault" insurance; that is, no matter who's responsible for the accident, and without regard to liability to any party - - employer or bus company - - your son is automatically entitled.
Now, at the same time, your son may also have what is called a "third party" claim against the bus driver and the bus company due to the bus driver's negligence.
For further details, your son should immediately seek the advice of a Worker's Compensation attorney, who will handle that end of the accident. Then, that attorney should be able to suggest a Personal Injury attorney to your son who will handle the "third party" claim.
Most all Personal Injury and Worker's Compensation attorneys do not ask for money from a client. They are paid either through statutory schedules (the W.C. attorney) or through a "Continegency Fee" agreement (the Personal Injury attorney) who takes his fee as a percentage of whatever money your son obtains by way of settlement or judgment.
The Worker's Compensation insurance company will be entitled to an "offset" for any monies they pay your son, against any Third Party settlement or judgment; i.e., if your son's third party claim settles in his favor, the Worker's Compensation insurance company will be able to obtain reimbursement via that settlement or judgment in the third party claim. The Worker's Compensation insurance company usually, but not always, agrees to settle for a reimbursement amount that is smaller than that which they have paid out to your son.
See an attorney today.
IAAL