If the SAs pick him up it is not an issue. SAs trump ROTC.
It is never binding in the way I think you assume. If your DS does not get an appointment and goes to ERAU, the scholarship is not activated until he passes the PFT in college.
No tuition, no stipend, no book allowance.
I get the guilt issue, but don't go down the road you are hurting another candidate.
Think of ROTC awards like hotels and airlines, they typically overbook. The chances of throwing back the scholarship impacting at this stage when only 1 board is left is minimal. They don't expect 100% activation.
You will also see on the SA forum side most posters will say keep it. The thing is at least 5% will not complete BCT. This is their insurance plan. 3 yrs ago a cadet tripped off of the bus on I Day, knee issues and he was turned back the same day. LY, a poster's DD contracted Guillame Barre disease in the 1st week, she was a recruited athlete and sent home. A few yrs back, an appointee played spring sports, broke a bone, and in a cast passed the I Day. Hence the Bubble Wrap joke.
They all paid the school deposit. They kept plan B in place until the last second.
Don't throw away the scholarship, accept it.