I would say no. No one gets access to what amounts to my account on my host.
I would pay for another domain/account/site for a few months. Use a debit card with a fixed amount on it. Give the person read only FTP access to the current site and a backup of the database. The person can do what he wants on the temp site.
When the project is done you can review the code and then move it to your real site. Same with the database.