Without letting the tail wag the dog, I first checked to see which airlines would best serve his needs.

After checking some route maps, Singapore and Thai have better coverage than Cathay into India, Nepal, and South Asia. See Thai routes here. See Singapore routes here. See Cathay routes here. So, based on his extensive travel to South Asia, I would recommend a Star program.
Note that in the Thai program, 10k within a calendar year or 15k over 2 years on any carrier on cheap fares earns Thai Silver status, recognized as Star Silver. Gold status requires 50k over 1 year or 80k over 2. Note that this status does not grant bonus miles, but does allow elite check in, etc., etc.

Star does have coverage in Africa via Lufthansa-- granted it's not as exhaustive as South African Airways in southern Africa, or Kenya Airways in eastern Africa, or Air France in western Africa, but find out if it's enough for him to get by. If not, then my hunch is the Air France / KLM / Kenya Airways combo in Sky Team should work for him.

If his travel is so extensive that a single partnership won't work, then I would suggest focusing on SkyTeam with links to Africa and SE Asia, but leverage the Thai program for Star Silver if for no other reason than to jump lines when traveling in South Asia.

Among the SkyTeam partners, NW has some special bonds between Chinese airlines that the other SkyTeam partners don't, so I would look to NW as the SkyTeam program of choice, especially given travel to Tibet.

Hope that helps!