We don't have a choice for FIFA dates ( the cup is a Fifa date) and without Son agreeing to be "injured" we cant keep him away, even if he is the country can insist on their own Dr and prevent him playing for us for the duration of the Fifa dates.Spurs needs to be selfish about Son's use going forward by the Korean Football Association.
It is a very sub-par entity that will run Sonny to the ground. Don't think even one moment that they will have any decency in protecting players.
The Games were not a Fifa dates and we didn't have to let him go, we did to have the chance that he missed NS and got him off of Fifa dates later in the year.
Son seems very patriotic and I think us preventing him from playing would only lead to him being unhappy, due to marketing and now no NS I expect he would have a queue of clubs willing to buy him.