Deleting meetings organized by long gone employee

[Robert K]

A user, joe.user@contoso.com, organized some meetings in the past. He left the company 6 month ago. His mailbox is deleted since 5 month. But now his meetings should be cancelled. Environment is Office 365.

MS recently announced here (https://portal.office.com/adminportal/home#/MessageCenter?id=MC106884) a Powershell command for that problem. But when I try 

Remove-CalendarEvents -Identity "joe.user@contoso.com" -CancelOrganizedMeetings

I get the error

"Object 'joe.user@contoso.com' not found in 'AMy.EURx.prod.outlook.com'". 
CategoryInfo: NotSpecified: (:) [Remove-CalendarEvents], ManagementObjectNotFoundException

Where is my fault or what is wrong with this command? 

[#2]

You cannot use the cmdlet if the organizer mailbox doesnt exist anymore. Instead, you will have to remove the items directly from the attendee's mailboxes. You can use some EWS based solution for this, there are sample scripts available on the internet.

[#3]

I still don't know why the Calendar Attendant doesn't just clean those up.