Are you asking if he will have to remove his shoes with the inserts to pass through security or will the shoes be stopped going through the x-ray because of the inserts?

Because of the medical issue, he MIGHT be able to keep his shoes on but without written medical advice, probably not. I know that is not policy but you should plan for reality and the reality is that many screeners do not follow the policy consistently. But as for passing the shoes through the x-ray machine with foam inserts, no problem. I do it every time I pass through security. All my shoes have such inserts.