I think you really need to consider the option that after all of the schooling, your son may not be employed in the US, so you need to plan for that.
My dd is an EE grad getting her MS degree in CS. She is being sponsored by her company to complete that degree so that they can transition her to management. She has indicated that she can’t hire international candidates because they don’t qualify for US clearances.
Have a back up plan just in case.