The main reason against accepting accounts as collateral is because we end up with situations like this one, where the lender needs to sell the collateral given to him when a loan is defaulted on.  I'm obviously against account sales, regardless of whether it's an account farmer selling a whole bunch or a lender who got stuck with one on a bad loan.  I'd absolutely love it if Theymos banned certain things on bitcointalk, and account sales is near the top of my list (scamming would take the #1 spot).  If account sales were banned, chances are that lenders might become reluctant to accept them as loan collateral.  Hell, I wouldn't mind having a rule against putting them up as collateral in the first place, but I highly doubt Theymos is going to make such a rule.

I'm not against freedom, but there have to be rules unless you want anarchy.  Also, I would point out that sometimes members put their account up as collateral for a loan that they never intend to pay back.  It's a sneaky way of selling their account, basically.  You'd assume that a borrower would want his account back and thus giving it to the lender would motivate the borrower to pay the loan back, but there are many reasons why that doesn't always happens.  I've seen numerous examples of lenders ending up with bitcointalk accounts that they have no real use for (DarkStar_ even mentioned he has one), and then what happens?  They have to sell them.  Technically they don't have to, but it's the only way to recoup their money.

I don't see a clear consensus forming here, nor do I see anyone tagging grtthegreat.  Some folks argue that account sellers shouldn't be tagged at all, some don't like exceptions being made, and some just hate DT.  I know I can't please everyone with anything I do, but if and when a situation like this comes up again, it would be nice to know what the community generally expects.  Even better would be some input by Theymos, but I won't hold my breath.