Watt's nomination is a strategic move for the President to have three kinds of influence on the GSEs. He wants Melvin Watt to be at the operational front door of the GSEs via the FHFA (Watt), someone at the financial backdoor (Jacob Lew - US Treasury Secretary) and someone on the roof via the FHFA-OIG (Michael P. Stephens - Acting Inspector General for the Federal Housing Finance Agency Office of Inspector General).
There is no necessary connection between Watt's nomination and the pending lawsuits. The nomination occurred in May before the lawsuits were filed. The President failed twice to replace DeMarco. First, he failed with FHFA Director nominee Joseph Smith in 2011 and secondly when state attorney generals and related organizations called and campaigned for the President to fire or remove DeMarco as Acting Director of the FHFA in 2012-2013.