In the vein of this question, I'm curious about getting a loan by selling treasuries. The issue, apparently, is that the proceeds of the short sale is held as collateral.
As I understand it, however, the prices of treasuries have an upper bound (unless negative rates are somehow possible but even so very rare). So there should be far less risk short selling treasuries than stocks especially when the interest rates are low.
Is there a reason why the broker still takes the proceeds as collateral and are there methods to short sell treasuries with minimal collateral given the lower risk?