Yeah, I'll need to update the rate over time, however at the moment they're set static to expire by 31st October. If I was to run them year around I'd need to run price feed scripts to periodically update their 100% backing collateral rate.
True if I lent at the wrong rate I'd effectively just be buying the BTS, however the other party in the deal would have to fail to repay and surrender their collateral, this in traditional finance would have credit score consequences, perhaps in the future people will track who fails to pay back loans over time