Is it extremely dangerous for a diabetic above the knee amputee to learn to walk just two crutches?

My fiance has waited more than a year, for his stump to heal after amputation. The nursing home has refused to give him crutches. They said that he might fall and reopen the wound. He now has a deadline from his employer about returning to work. He has gain over 100 pounds waiting for the healing. I now feel, that if he starts to walk on crutches, he could lose some of that weight. I want to know that if I attempt to teach him to walk with crutches if it will be an impossible job for a layperson?