The mercy comment, was that even when it depends entirely on pogs, it doesnt mean he HAVE to wait for pogba to make his mind. He very well can and and im pretty sure he IS working on pogba whenever he can to make a move. In fact, im pretty sure that between him and pogba everything is said and done, and he has explained him very well what his future holds and what he will give to pogba obvs all of this fueled by his own benefit, not necesarilly what benefits pogba sporting wise.
And why he has to sell pogba?. Well the most obvious reason, and the reason the world is like it is: money. Plain and simple.
Just think about the money he will receive of his sale. And he is not selling him for the worst of his client economic wise, he will guarantee his client gets a fat contract in a top team on the process.
What happens after that is on Pogba's hands, but him, as his agent, will have fulfilled his mission, and made money on the process which is all of this about(for him).
His mission is to make money foremost, as any good business man. You cant make money from fairy tales and sporting love stories.