From the article:
The accusations have been used in the German press and politics to try to negatively associate the AfD with China and discredit the party and Krah.
That was exactly my thought as well. It's probably just a way of attacking a conservative politician.
Out of curiosity, how many other employees of members of the German government have been arrested recently on suspicion of spying for China? And what party do they belong to? Or is it only this guy, and only Max Krah? Why has Hunter Biden, for example, not been arrested for spying for China?