Both are people who are seeing bubbles in bonds with a burst nearing… Biderman has a good big picture, and Kumart, of TCW, is yet another expert on bonds who appears headed for the exits. Note that as these people see money flowing out of DEBT (bonds, etc) that they see it flowing into commodities.
The latest rumors are that the Fed is likely to continue purchasing GSE paper basically extending their March deadline as they know that removing that artificial support will result in much higher mortgage rates. In this way, the entire market is FALSE, it is underpinned and propped up. Remove the support and down it goes. Can they keep the support there forever and ever? I think not, eventually we will all pay for their greed and misinformed methodology.