Yup, buy back policy very different with QE. I see it as an act of caution because the size US of government debt, Treasury must continue to issue a large volume of new bonds, which bring a little over supply on market. The market is burdened by various types of bonds, and some of the older bonds are less attractive. These less liquid bonds that are bought back by the treasury. Activities to streamline the debt market will not affect Bitcoin.
But it will affect bitcoin if after buy back, government still have to issue new debt in very large amounts to covering the deficit and in the longterm, these will affect asset such as bitcoin and gold. Because even at this time investor still trust on US, but who knows when US debt getting bigger and bigger investor start thinking about rebalancing between scarce asset or asset in the form of obligations of other parties, because nowdays debt supply, financing cost, the tryst and confidence in the US fiscal balance are becoming important macroeconomic variable.