I would bet that PSG probably agreed with Silva (verbally) that if Marquinhos is able to join their ranks he is free as they have his replacement.
PSG wanted obviously to hang on to one one of the best (on form CBs) in the world, not to mention his "Puyolness" or in other words leadership and on pitch respectful personality. He is PSG's captain yet on his first season.
Being a champ after so long then loosing many of the possible winning recipe like "Anchelotti", "Leonardo" (though he was too animated) and now the backbone of their defense... it has to at least come after they feel a bit secure.
Here in Paris not many would agree with me, they find that Marquinhos is an addition, simply. Hope they are wrong... We need this guy!