It is outright scamming, you aren't supposed to SELL accounts and associated trust
The selling of accounts is allowed, though I think most people in the community frown upon it or don't condone it, but nevertheless it is tolerated by the mods and admins.
Yes, it is allowed simply the mods and admins cannot enforce this rule and spend their days searching for shill/bought accounts...
They rely on the members of bitcointalk to help, and they are pretty damn good at it.
Buying acounts is frowned upon because pretty much all the purposes for buying an account is scam, scam, and more scam.