The poster did not appear to understand how the Federal Reserves works. Here are the accounting entries as they would work on the books of the Fed.
1. Create Fiat = Debit Cash, Credit Equity
('Cash' on the books of the Fed is not in circulation but can be used to 'buy' debt or assets (homes, land, etc) as authorized. As we have seen, the Congress will 'authorize' any number of 'assets' for the Fed to 'buy' to avoid deflation. Charter 'restrictions' on the Fed mean nothing and can easily be changed. BTW, you or I would get tossed in jail if we made accounting entries like this. The Fed is 'special'.)
2. Buy Notes/Assets = Credit Cash, Debit Investment
(Place Cash into circulation.)
3. Receive Payment = Debit Cash, Credit Investment
(Again, cash on the books of the Fed is not in circulation and has been removed from the economy.)
4. Close Original Entry = Credit Cash, Debit Equity
(Reverse original entry 'destroying' cash.)
Lather, rinse, repeat...
The Federal Reserve is creating 'money' out of thin-air any time they buy debt or assets of any kind. Fiat on the books of the Fed is not in circulation. Receiving cash for debt they purchased with cash they created out of thin-air simply reverses the original cash-creating entry and the 'money' disappears from the economy. This is why a fiat currency must have a continually-increasing debt-load for the economy to 'grow'. Fiat has no intrinsic value. It's 'value' is psychological.
Not when they roll over maturing debt. Or, in this case, reinvest principal and interest received on MBS.