Repeated selling is one of the easiest ways to come to our attention as a potential "commercial" hobbyist (although not the only way). When someone comes to our attention, we examine the entire situation and enforce our rules impartially. We have a long history of enforcing the rules the same way. We don't make exceptions for "good guys" (or gals), or even members we like. It wouldn't be fair to the folks we've tagged as commercial in the past to suddenly decide we are going to make exceptions.
It also makes no difference if a member is a sponsor or not - sponsors are not allowed to sell (or advertise themselves) anywhere but in their paid forum.
As far as others who sell more, or more often than some who have been identified as commercial, RC gets thousands of posts every day. We don't see them all. If you think someone is violating RC's commercial posting policy, report the post and we'll look into it. If you don't report the post, then don't complain about what you believe is RC's "selective" enforcement.
Finally, RC's mission is the exchange of information, not commerce. Don't think for a minute that selling frags and equipment is what RC is all about. Selling/trading on RC is a privilege allowed to members who contribute to the mission of the site, and there is a fine line between between hobbyist and "commercial hobbyist." Keeping RC "commercial free" (as much as we can) has helped make RC one of the largest bulletin boards out there (not just in the hobby). So, if we feel you have crossed the line, then we take action. I emphasize "we." The Moderators on RC make decisions as a group. It's not one Moderator making all these decisions. Each and every situation is reviewed and agreed upon as a group. It's nothing personal (quite the opposite). It's just the way we run our site.