This comedian has a reputation for being willing to mess with people who are difficult to deal with, or are in a minor position of authority.
In this case a friend referred a scammer who is attempting to extract rental deposits prior to viewing the property to be rented to Joe Lycett's attention.
It's always a good idea to know who you're dealing with or at least be cautious and use good judgment. In this case the potential for comedy material outweighed the good sense to be cautious.