Hippolite,
The EC225 has control locks on the collective and cyclic.
Although I never left the controls unattended while still running, I can understand the reasons some people gave to justify it in their field of work. There will be inherent risk in doing so but as a previous mentioned reason getting stuck in the outback because the helicopter will not start after a shutdown must have its risks as well.
Greetings
Finalchecksplease