I understand why PSG want to make it as difficult as possible for Neymar to leave. If they let him leave it will open up a door for Mbappé to leave in a year or two and that will be the end of PSGs project.
Since my fellow PSG fan talked about Pogba, i'll use his example.
Zidane and Real wanted Pogba. Pogba wanted to leave and even said it publicly. Even his brother(s) said it (in Chiringuito?). Now, Real didn't fork out the money MU is believed to ask (180-200 M€). What happened ? Nothing.
Here, PSG is even accepting players in the transaction. And it is the end of the window (meaning PSG can't even turn around to pick players of their choices). I can't imagine how you think PSG is being difficult here.