This all sounds great on paper, in reality different parties want different things and often they can't come to an agreement, this happens all the time, it is not about who disrespect who, just wants/needs and differences that can't be bridged.
No party should punish the other party as long as the initial agreement/contract is not breached.
I wouldn't say it's on paper.
The bolded part you write can describe fine the negotiations process, not what happens afterwards.
Yes, agreement cannot be reached many times, but from then on there is a portion of decision that each of the contracted parties is at least ethically allowed to exert.
Dembele and his agent want to take away that portion that the club is ETHICALLY entitled to (decide when to sell or to keep for 1 year)
[The opposite case would be Levy taking away that portion that Kane is ethically entitled to (decide to not renew with Spurs and play elsewhere)]
They will now face the consequences, which are ETHICALLY more than fair.
Legally its also OK for a player not to enter the squad, and the Spanish Footballer Association is BSting in their letter.
PS: Yes, Mbabe totally respects PSG because he is not taking away that portion of autonomy and decision from his club.
He is only exerting his own part