I'm not so sure it's that clear cut. There's no onus on the employer to alter work practices to make allowances for an employee who now suffers from a bad back or other injury. I was involved in a case previously with an guy who got injured outside of work and was not capable of returning to full duties, the legal advice at the time was if he didn't show for work and perform the usual duties, it could safely be assumed he had relinquished the role. Thankfully we're a nicer company than that so after giving him over 6 months paid off to attempt rehab, when that didn't work out he was offered redundancy.
So if the OP's job always involved moving heavy bags of laundry, and the employee is now and forever incapable of that, then the employer does not have to adjust the role to account for this.
However, there is definitely something in the lack of training provided in manual handling and the injury incurred and their handling of an injury sustained in the course of their work.
The OP hasn't posted since the original question, if you're still reading, I'd strongly advise your relation follows Sue Ellen's advice and avail of the experts.