The former Utah governor is way ahead of 82-year-old Orrin Hatch in polls of his strength in the upcoming senatorial race, so Trump's taking him out of play. Of course, Huntsman is free to reject the appointment, and perhaps he will, but he went along with Obama's appointing him ambassador to China when that president saw him as a political threat, so I'm guessing he'll accept this one; he's only 56, and probably has a deal to defer challenging Hatch until that old man decides to either retire or die.
Huntsman's served as ambassador to two Asian countries now, Singapore (Bush) and China. His expertise in Russia is unknown, but that doesn't matter in national politics. Curious, at least, that Trump is willing to forgive and forget that the man called for his withdrawal from the presidential race as recently as September.