Still silly, if they aren’t confident to weed out Russian spies with Russian nationality, they are even less confident to weed out Russian spies with other nationalities. I would think that most undercover Russian spies don’t have Russian nationality, because that is an obvious attribute, which is easy for a government secret agency to change.
There really is nothing better than background checks, and privilege separation for this kind of stuff.
Banning AfD is the best short term solution, it needs to be followed by a stronger social focus of the government.
One reason for conservative and right-wing sentiment is fear of the future in the populace. Fear causes people to try to isolate themselves from “others” and wanting to horde and protect their stuff instead of supporting others.
If the government is able to alleviate those fears, they will not see a need for fear anymore. But that is a long process, which constantly gets sabotaged by commercial outrage media, foreign intervention, social media, conservative/right-wing politicians, etc.