Maybe I'm not understanding correctly, but from what I could understand, Napoli has a contract with Osimhen in which, in that contract, Serie A teams will not be able to sign Osimhen, if I'm not mistaken:
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They don't want to reduce his price, they don't want him to play for Napoli, but they force him to go to Napoli's friendly matches. This just shows that Napoli wants to destroy his career. They are pressuring him to accept Saudi clubs because that way Napoli would make a lot of money.
Napoli indeed could extend the contract of Osimhen up to 2027 and the release clause of €75m could not be lifted by another club in Serie A, which means that the player has whether to prove himself useful and fix things with Napoli or accept to move to Saudi Pro League with Al-Hilal or to another European team that is willing to pay the clause.
The first option is difficult to achieve with all the problems he had there. Main benefit: a chance to play UEFA Champions League, secondary benefit: try to get the scudetto again.
The second option: more money in Saudi Pro League, he will be very visible there. Drawbacks: no Europeans competitions and it will be difficult to return to a top European team in a top league.