I know It's allowed to sell/buy bitcointalk forum accounts but I have a question If It's allowed to rent a bitcointalk account for a specific time?
The borrower could do stupid things with the account and make it full of negative trust feedback and make it worthless.
The lender could claim the account has been hacked and send theymos a message signed by an address used earlier and get it back.
Either way, it is not going to end well.