Another good imput from Marcel, a lawyer always doing a great job on this platform, as Steven too.
"If he arrives by plane, here is a link explaining airport asylum procedure: ****://***.asylumineurope.org/reports/country/Germany/asylum-procedure/procedures/border-procedure-border-and-transit-zones
Applicants from Nigeria are not automatically granted protection in Germany (like from Syria). He needs good proof that he is fleeing from Boko Haram. If he has no proof at all it can be that he is immediately sent back at the airport (see link). If, on the other hand, he has some proof, he will have a normal asylum procedure (in which his special case will be examined)."
Best,
Paolo (and Marcel =) )