That call will not "minimize all windows on the remote computer", it will minimize all windows that were launched by the interactive desktop shell for the user who executes the call. An SSH session is launched by the OpenSSH service, not a desktop shell. I don't think that's going to work for you.
You could try using the task scheduler and create a task that executes Powershell and your script. Set the task to run as the use "INTERACTIVE". Then on the local PC run "schtasks /run /s remote-pc-name /tn Your-Task-Name". The desktop user will see a Powershell window pop up when that runs.