That unusual. He’d only be obliged to continuing his job during his notice period. Not a different job. Sounds like he didn’t know his rights.

Most UK contracts will also include a clause allowing the company to end the employment immediately as long as they still pay out what the employee would have earned during their notice period.

Having been through a few roles in the uk myself, the obligation on the company to give me adequate notice (and pay) has always benefited me.