If Son Heung-min had said he'd retire if people didn't listen to him, everyone would have told him to just retire.

Do you think people would have taken his side here?
They would have just insulted him even more.
They would have said, "He's already old, why is he using retirement as a threat?"
Since the topic of retirement keeps coming up, they'd tell him to just go ahead and retire if that's how he feels.
They'd say, "You're not that important."
It's the same with Son Heung-min.