I agree that your friend needs to pitch his CV very much on how the skills and experience he acquired during his military career can benefit a potential civilian employer. He should avoid over emphasising his officer background which could create a wrong impression. I have worked with many ex-military controllers and have in most cases found them to be professional and good team members. However, in other cases, the officer training seems to have created individuals with an over optimistic view of their own abilities which can antagonise colleagues very quickly.
I suggest an Aerodrome rating without a Surveillance rating will not generate much interest from potential employers. However to get the necessary qualification will involve taking an expensive bet on the future.
If he really wants to stay operational, he should be prepared to accept an ATSA job as a way of getting on the inside and then later on possibly getting financial assistance from his employer to do a course for a Surveillance rating. He will be able to find out if that path is available by having a chat with the unit SATCO. Alternatively, his ATC experience could be useful to an organisation like NATS in an office based role.