Son getting screwed?

He’s been a poolee for a year and ships next month. The recruiters have given him the picat numerous times and his last score was a 60. All year he’s been told he will get his choice of legal specialist but suddenly yesterday at his IST the new Gunny at the recruiting office tried to get him to sign something that said he will go into logistics. He didn’t sign. As an Army vet it smells like BS to me, trying to say the previous Gunny didnt follow protocol telling him he could be legal. Any advice?