Rodney had worried whether John would think that Rodney thought he and Evan weren't business savvy enough to do up their own website, and be insulted that he set one up for them.
On one hand, it’s very personalized, what with Rodney designing it specially. On the other hand, he can't be sure it won't come across as interference in John’s (& Evan’s) business. It’s along the same lines as John sharing his personal Tardis design - perhaps a little presumptuous but very sweetly meant. After all, this isn't just sexual involvement. They’re building a life together.
He needn't have worried. The parlor is so busy that neither had had the time to even start researching how to create a web presence. Quite the contrary, they were grateful (if a little apprehensive about the long hours that more customers might mean).