It's ridiculous to think that a country wouldn't take back their own people. One has to wonder if the reason they were rejected was because these people involved had ties to terrorist organizations. I wouldn't blame the Vice-Chancellor for withdrawing aid from this country. I mean for all we know he could be funding terrorists and not even realize it.
I think it is plausible that Germany can decide what type of aid they want to give to the countries they want. And after welcoming so many asylum seekers, the face that they are filtering them is normal and should be understood. The african countries that don't follow this logic can be cut from aid.
If Germany wants North African countries to do certain things, they have a right to make those things contingencies for receiving foreign aid. Germany does so much for the rest of the world. Germany needs to begin to look after its own security. Germany has every right to insist that certain things happen if Germany is going to hand out money. It's pragmatic.
Countries that are generating huge numbers of refugees need to be responsible for their citizens. Nations such as Germany are not responsible for individuals who don't meet their criteria for granting asylum, and need to exert pressure on these countries by completely suspending aid programs. At the very least, a per capita aid reduction should be imposed for every returned refugee who is not repatriated.