A popular open source security scanner recently went proprietary, complaining that their community never contributes much. We are sorry to hear that, but happy to report that the Nmap community is as vibrant and productive as ever! We would like to acknowledge and thank the many people who contributed ideas and/or code to this release (since 3.50). Special thanks go out to Adam Kerrison, Adam Morgan, Adriano Monteiro Marques, Alan Bishoff [ huge list goes on and on
So if Nessus can't get enough help, maybe that says more about how they run the project than their suggestion of an open source community of leeches who don't contribute back.