we went late June--flights looked great--wide open BE all 4 legs. That changed quickly during week of travel. With the high ratio of no-shows, we made it in BE 20yrs seniority S2. The S3B parent sitting behind us--not so lucky--was removed in Dakar on his return trip--good thing he had experience with bumping and the city/hotels/transport. That was 07 when there were no embargoes.
I would tread very cautiously--the fees are pretty high, too--about $150 airport charges, taxes, etc PLUS the mileage for S4.
If your buddy really wants to go, make sure they have all the info and wherewithall to make it to a hotel in Dakar and prepare for possibility of several days delay. Or--have alt route (good ol' Plan to get elsewhere to get home sooner. I'm not sure about any visa on arrival fees, tho--what about yellow fever? It's technically required for travel from YF zone to SA, but I don't know if it's enforced, but if they deplane in DAkar it could be an issue. I do know that Accra has $100 visa on arrival fee and SA requires a full unused passport page with 30 days validity after return date...blah blah blah.
I know it's disheartening, but that's the experience I can share.
Good luck and keep us posted what happens--or doesn't!