tempdb is rebuilt from 'scratch' every time SQL Server is restarted.
It rebuilds it based on Model. You could try giving the person permission to Model and Tempdb, stopping SQL Server and restarting it, then seeing if they still have permissions to tempdb. But why are you allowing users to do things in tempdb? It's just what it's named - a temporary database. Users should be creating or using their own database(s).
-SQLBill