I'm not going to attack players who play for their national teams. Indeed, I might be one of the few on this board who is looking forward to Leonard playing for the US when the time comes. I think playing games in the summer can be a good way to stay in shape, while allowing some players to play roles they can't in the NBA. And , as a fan, I want to see great players play as much as possible. But I don't think your characterization of the argument against NBA players participating in FIBA tournaments is correct.
From what I gather, people are not upset because players are, as you put it, representing their country above any business consideration. Indeed, they're NOT doing that, hence the need to get insurance and the general reluctance of many players to forgo tournaments while they're free agents. Players are very well aware of the business considerations of their participation, and they take precautions to protect themselves.
What people see as the problem with this is that the NBA teams then carry the risk for the player, while receiving none of the gain. (So goes the argument. Pop disagrees with that part.) In essence, Parker in this case isn't taking any risk himself. The Spurs have to pay him even if he breaks his leg while playing in September. Although insurance would compensate San Antonio, they'd still lose out on investing Parker's $12.5 Million into making their team better, or at least get diminished returns. Even if Parker survives the games unscathed, if he runs out of gas later in the year because of his extra games in September, then it's the Spurs and not Parker who will have lost out on the money they could have gained.
Players aren't putting nationalism over money by entering the tournaments. If they were doing that, they'd assume the financial risk themselves. Instead, they get to have their cake and eat it to. What they're actually doing is choosing their countries' interests over their NBA teams' interests. They're risking screwing over their NBA teammates for their friends and family back home. There's nothing particularly virtuous about that.