The memory foam slippers? If they're comfy should be just fine.
However, should there arise a new ulcer in that area, it'll be harder to treat as there will be scar tissue to deal with. [Cuts, blisters and the usual boo's]
Thing is to constantly CHECK and then recheck [2x's a day] for problems and address them before they become BIG problems. Prevention and avoidance are the best and safest approaches to this stuff.
Alan should know what is right/wrong with himself. He should know best. If you need to help him do so? Do so. Good luck! - j