I can answer this, although it's pretty obvious... this site endorses the sale of Steam accounts. That alone is reason enough for Valve not to want people being linked here.
Interesting. Maybe send them a customer feedback and ask them why you can't link it?
The site is not malicous... it endorses the sale of Steam accounts, do you honestly think Valve would stop people from getting on here if they could?
Support won't do anything, I doubt this site is very popular with Valve. Same for Jagex.

