Validate Owner field. Require tha user changes the value.

I have a situation where I need to require that the person creating a record (Custom Object 01) re-assign the Owner to another user.  The Owner field does not allow Field Validation or Default.  I cannot create a custom field because I need the user to be able to choose from a list of Active users and the Owner field is perfect for this. I have tried creating a Workflow validation where I compare the current value of the Owner to the new value, but nothing seems to work. I have tried various formulas, like:

[<Owner>] = JoinFieldValue('<User>',[<Owner>],'<Alias>')