In my experience, VA benefits are not affected by requesting a loan modification on a VA loan. I have been able to obtain what is called a VA-HAMP for clients in the past. It's a branch of the Making Home Affordable Program. Your son and his wife should look into this program, I included a link below.
Please thank him for his service to our country.
Additionally, myself and many other lawyers on here provide free consultations. If he'd like to call and chat about his options, please let me know.
Gregory Nordt, Esq.
This is not designed to be construed as legal advice.