If it was google calendar access then I’d be asking why his contact card is showing him as staff and more importantly, why it’s in outlook exchange server at all.

Outlook exchange server for storing contacts and having email access to a google calendar are two completely different things.

The only way I can imagine this is set up is that they are using G-Suite, which is organisational based. That -still- doesn’t explain the name card or why twitter banned this dude.