To your first question, while Mnuchin and Calabria didn't literally stop the CASH NWS payments of the NWS on "day one" of Calabria's term, they did so before ANY cash payments accrued from previous Q could be paid, so just as effective as stopping it on day one. Under Calabria not ONE cash NWS payment was made from the GSEs to the government, this is factual. This highlights Trump's view that to recap they must first stop the cash sweeps which they did before any further payments could be made so the GSEs can start accruing capital on their balance sheets.
Regarding your second question, yes the liquidation preference would increase if the GSEs were refunded the ~$45b in cash NWS payments most likely, but shareholders much rather have that $45b on the GSE balance sheet (would get us to $112b of total capital today), and more importantly it would require the government to write a $45b CASH check to the GSEs which hopefully should prompt settlement. I'm sure someone in the Biden admin is telling him ya we can pay this $45b cash check as required, or we can just wrap up privatization, settle w/ shareholders, and monetize an extra $100b instead for your housing agenda now that BBB failed.
To recap GSEs currently have $67b in capital, at the end of the year that will be closer to $75b. New minimum requirement is $180b and they are earning ~$30b a year (so ~3 years to organic earnings retention). But in Collins case, worst case the Judges don't agree privatization would have been completed in time if Trump could have fired Watt day 1, the GSEs at a minimum should get over $45b in cash back to balance sheet since the NWS suspension would have happened before any further cash NWS payments could be made instead of 2 years later as Trump stopped the cash NWS payments immediately so no need for hypotheticals (Yes the liquidation preference would go up, but the government would still need to write a $45b CASH check in exchange back over to the GSEs which is definitely not a desired outcome and hopefully prompts some kind of resolution). This would cut ~3 years down to ~1.5 years to get to $180b of cash capital on the balance sheet. At some point the government should be forced to deal with this issue as not only have the GSEs been completely reformed for the better but now have their desired cash capital on the books. (Not to mention Lamberth and Takings are ticking time bombs, + midterms Biden will most likely lose Congress, BBB is dead, so this could be an administrative win for him if his hands gets tied).