to build on the nice questions above - does your DS have prior service - is he green to gold? Is he on scholarship? If the Army paid his tuition/ fees/ books stipend in college via a scholarship, unless he is in the SMP / guard which is reserves focused, I would expect he'll serve in active duty to honor the service commitment he made.
- Non-Scholarship graduates may serve three years on active duty and five years in the Inactive Ready Reserve (IRR). Scholarship graduates may serve their commitment followed by four years in the ready reserve.
- If you received a four-year ROTC scholarship, you must agree to serve four years full-time as an active duty Army Officer after you graduate and then either extend your contract for four more years or serve four more years with the Individual Ready Reserve (IRR) where you'll return to civilian life but need to be ready to help in. If he trains to be an aviator, then the service commitment is longer.
wrt a job offer, hopefully he understood this when he signed up -
he already has a job after graduation, that he's been training for, for years. full time job, great benefits, and can gain leadership experience and expertise that can be highly recruit-able when he ultimately leaves the service. Encourage him to understand the full package including BAH, meal allowance, base pay, and after 2 years a 5% match in as part of the blended benefits offered. He should also understand veteran benefits, life insurance, etc. They pay so little in taxes because the BAH, meal allowance are not taxed. Encourage him to understand the increasing payscale as they advance in rank and promotions that may make this very competitive vs a higher paying civilian job where you pay thousands for benefits, etc.
The knock on this graduating generation is that they are affected by FOMO or lack loyalty. Of course that's a generalization - but he's engaged to a nice fiance named US ARMY. so maybe he shouldn't be courting other people - he put a ring on it

If he wants he can also speak to the unit about paying back the scholarship for recoupment and skip serving (but you didn't imply that in your post). Good luck and please let the board know what options the ROO outlines in their upcoming discussion.