I think the suggestion about the ostomy nurse is a good one, too. However, I think that you need to explore with the man his revulsion at his body changes, which could be at least part of his problem.
In the very old days, I worked with post op patients whose surgeon didn't believe in putting a colostomy bag on patients post op. He wanted a dressing. So these people would stool all over their abdomens. I had a client who had actually a fairly distal colostomy and, over time, it could be expected that her colostomy would produce pretty formed stool, but now she had liquid stool regularly spilling onto her abdomen. I gave her that simple information [that her stools would eventually be more formed] and that, with a bag, her situation would become more controllable. Months later, I met that woman casually and she told me that that information had given her hope and helped her to believe that her situation was going to be, somehow, manageable.
The odors of that colostomy, odor stoppers aside, are going to be a fact of that man's life. He needs room to express his fears that, when he walks into a room, everyone will smell him. He needs time to talk about how out of control he feels about his stools and the odors. Maybe he needs to meet someone with a colostomy who is coping. Maybe he needs to hear from you how you cope with being around obnoxious odors. I always plug my nose by pressing my tongue against my palate. Maybe he needs to be taught to care for his colostomy in the bathroom so that bathroom odors stay where they belong and he doesn't have to contend with them in his living space, his hospital room. I don't know this man, you do. But he needs time to tell you these things and maybe you can help him find what it will take to help him cope with this momentous life change.
Good luck to you and your client.