I would say he would know mate, simply because it's in their reseller agreement
http://whmcs.com/resellers/
Reseller Requirements
You may only sell licenses to your own hosting/dedicated customers
And
Q: Who can I sell these licenses to?
A: The reseller program is intended for web hosts, to allow them to offer WHMCS licenses along with their reseller, VPS and/or dedicated hosting services. The reseller program does not allow selling licenses to the general public, or as a standalone item.