$HDUP, I am so happy that we have a genius among us...on a "low" horse. So yes, you can put them up as collateral, but you CAN NOT TRANSFER THEM, the MM won't allow that.
So what does that mean? It means that anyone lending money against those shares is probably pretty confident that if the loan is not repaid, that the shares will be tradeable (OFF the CTO) and they will be able to cash them in.
I'd suggest that the party lending money knows the collateral will have value. If the CTO isn't lifted then their collateral is worth ZERO.