Court decision: agree or disagree? I read the Judgement and I found section [50] to be key for me - WML wasn't just supplying access to land that was being used for a hazardous activity, the land WAS the hazardous activity.
[66] onwards with regard to the Risk Assessment process. If WML had assured itself the tour companies were completing their own robust risk assessments using regularly updated expert advice, for example, changing the tour schedules according the volcanic activity alerts, would WML have been found guilty? If the tour operators had been performing robust risk assessments it would seem not "reasonably practicable" for WML to duplicate their efforts.
To answer Peter's question though, it doesnt matter whether or not WML had its own workers on the island if it had control. And it was judged to have control. So Yes, I agree.