They are probably giving him 9 weeks notice of termination of contract, in which case they will pay him for the next 9 weeks, and dismissing him for the (potentially fair, I'm afraid to say) reason of capability. He is unfortunately not capable of doing his job.
However that shouldn't be the end of it if his sickness is a direct result of the accident. Employers have a duty of care to their employees and if they fail in this regard he is entitled to make a claim for work injury compensation. If proven, one facet is the potential loss of earnings in the future.
There are lawyers up to your armpits specialising in this, but in the first instance it might be wise to talk to the CAB. One has to make a claim within 3 years. If he is a member of a Union, they will probably take it up on his behalf.