How can I link a text field to a user profile such that I can display nodes on the user profile based on that text field
I can see how you'd want the Producer to be able to create an event and assign instructors to it before the instructor has an account. So in that case, have a node type which represents the instructor. This would be like a bio page or CV or some-such.

Then use nodereference and/or entityreference fields, Views, and viewreferences to connect the dots. The Event type would have Instructor fields which would refer to the bio pages for the instructors. As the instructors created accounts, a viewfield on the user profiles would show the bio page, keyed by an email acct field which you'd be sure and add.

Complex but not hard. :-)