To bring Adams in, the program needs to find about $35,000 to cover the cost. About $25,000 of that is for insurance. Considering that Adams is now a millionaire, they've got to pay that money to cover his contract in the event of, presumably, an injury.
High Performance Sport New Zealand, previously funded New Zealand's national teams. However, after forking over $1.5 million for the last four-year period and not seeing the team make the Olympics, they've cut funding.
In essence, Steven Adams is such an expensive entity, his home country's basketball program may not be able to afford him.
I know little of such things, but wouldn't be surprised if this still gets done. Adams could be the top basketball player to ever come out of New Zealand and it's difficult to imagine $35K gets in the way of this. Assuming it's legal, an entity like Adams' own Oklahoma City Thunder could step up and foot the bill. But they're probably not in any great hurry to let Adams go and risk injury. And with the games next month, they would probably rather keep him in the U.S. to prep for the upcoming season with his new team.
Also, keep in mind that this is just one tournament. There will be other opportunities for Adams to play for his home country down the road. Still, it's surely frustrating for the country not to have perhaps its best player.
Will be something to watch over the next few weeks.