Is he really being paid to play? Surely raising the profile of PSG in the world and selling merchandise are much more important than playing for a few minutes per game.
It is good of him to give to charity. Mind, if he didn't, the only winners would be the 'fisc', the French Inland Revenue. He has to be paid some salary, since the fisc would query his working for nothing. But he may run foul of the French claim on a percentage of all income worldwide unless he doesn't get benefit, but he has it paid to charities. Otherwise he'd only be able to claim relief against income received in France. He's also living in a hotel, to avoid evidence of residence by buying or leasing a house, and he's contracted for less than six months, to avoid establishing evidence of residence by length of stay. And notice that his family is not with him, to further distance himself from being resident.