To be honest I would not leave the powershell command text very open ended. Imagine the scenario where the powershell command is in a txt file in a shared drive and local robot users have quite extensive administrator privilages. In that case if a human user with or without bad intentions, edits that txt file and all your VM’s can be affected by that. In my case I designed in a way that the powershell is hardcoded inside the activity and a change can be implemented by publishing to the orchestrator. This command is not something we would change frequently anyway.
Best