Because the slower the recap, the higher and more prolonged the risks are for taxpayers and the housing finance system. The whole point of having lots of capital at FnF is to minimize those risks. Ergo, the more capital they have sooner, the safer they are.
Watt was of the mindset that FnF's capital didn't matter because of Treasury's backstop. Calabria has a very different mindset. It is crystal clear from the capital rule, his interviews, and his public comments that he wants lots of capital and wants it ASAP.
In the end, you have things backwards. A fast recap is good for everyone except current common shareholders. Dragging out the recap to use more retained earnings only benefits current common shareholders while exposing taxpayers and the housing finance system to unnecessary risks. Doing so on purpose would be a severe dereliction of duty on Calabria's part.