Well i have a few arguments:
1) I work for SkillRoad and i don't even touch the BTC
2) We do need every contribution possible as hardware and human work are not for free...
3) We are promoting our community outside btctalk, and as you already know people come here to register for the first time, so don't be surprised about it!
4) If you think that the only thing that makes a sockpuppet is activity then you should reconsider.

ohh and the last one we are currently developing a efficient formula that will help us identify those who take advantage of the system. Stay tuned for more info, as we will open a special thread to discuss this matter!