If they held the bonds in a trading book which was marked to market the losses had been incurred already as the secondary market price of the bonds dropped. So, reducing the exposure by selling the bonds for cash does not incur an immediate loss and improves liquidity while giving up the possibility of recouping if the value of the bonds rises again.

If they held the bonds in an investment book on hold-to-maturity-accounting, they did indeed realise losses.

Economics is politics by other means