The only working solution I found is to do this on Exchange Admin Center (for all users on the domain).

https://admin.exchange.microsoft.com/#/transportrules
Go to Mail Flow --> Rules
Add a rule: Is message type 'Calendaring'
Redirect the message to other user, or delete the message.
This will have the effect that the user will NOT be able to see the meeting request. If you redirect it to another user, they will be able to see it, AND it will show up on their calendar.

Keywords: Outlook, Exchange, Calendar, Meeting Request, Event, SPAM