This has been discussed before. I remenber I spoke about it on a post, long time ago.
For me, team manager should decide if the player goes or not to NT. Not only for first time.
Maybe is a problem for some NT, but in my opinion law should defend to the club. I mean, sometimes, NT doesnt help you to improve your player, calling the most value players on friendlies or using his own players to his benefit, or use friends players, or he doesn't take the new youngs from camps (but then, when the club make he play a lot to improve they want to call the player) or play with hard tackling in friendlies. So for all this reason, IMHO, team coach should have the faculty of decide.
In real world, some players have said no to NT. In Spain, we have the case of Oleguer, he said no to NT because he feels from Catalunya and not from Spain. But there are more cases round all over the world. Puyol, for example, said to NT no because of the age, he has too much injuries, and he cant play so much matches. In real world a player, could decide, here, we ( the team coach) are the voice of the player, so I'm agree with Luiggi (but for all the matches, without restrictions).