I completed a long a I dare say scathing response to this. Then the internet crashed and I lost it. So, I'll summarize.
1. The fact that your psychologist is FAMOUS means nothing. Get over it. It says nothing about his ability or his advise. Telling us that only serves you in putting him on a pedestal where you can belittle the "un-famous' advice you receive here.
2. There are many swingers that see sharing there partner as the ultimate form of intimacy. A gift if you will. IN fact, many would say that their relationship benefits from the sharing.
3. Exclusive is a control thing, not a giving thing, especially if it is one way. IE you are telling your wife she must remain exclusive or ...... It is simply an agreement, but that doesn't mean that when couple decide not to be exclusive they can't build intimacy or connection is a special way.
4. As I sit here in my 44th year of bliss with my high school sweetheart, I can tell you that our intimacy and connection is as strong as ever. Swinging is just another part to our adventurous and committed relationship.
Now your psychologist may know you better than I. He may know that you are not open to, prepared for or interested in sharing your wife, but to draw broad generalizations is just wrong.
What I'd want in a psychologist is an open minded individual (famous or not) that would help you explore your feelings around her request, help you to articulate them without judgement and help you and your wife explore, together, without judgement or wrath why she might want to swing and how that might work or not work for you both.