I'm sure that Klinsmann would counter that he thinks it's absurd that Mix should miss a whole international game window just to play in useless friendlies for NYCFC.
Not saying it's true or that I believe it, but there are two sides of the coin.
I'm sure Klinsmann would have a lot of things to say, but the fact is that Mix has been playing with the USMNT for a while and knows the players, strategy, coaching, etc. NYCFC is a new team for him, and to me it seems more important for him to get acquainted with his new team and coach. Plus, he will be playing a lot more games with NYCFC this year than with USA. To me his time seems better spent with NYCFC.