[ThePadawan]

I'm going to contradict sibling and say "Yes".

It's just a Verein (untranslateable, but let's say 'private association/club') with members.

They can refuse to accept members for any reason, and they can kick out members for the reasons they themselves specify.

Currently this section (§14) reads they can kick out members "that are a danger to the purpose of the association or are harmful to its reputation or interests".

So (read cynically) pretty much any reason.

[germanier]

Note that in this case, a two-thirds majority in the general assembly of members have to confirm the kick-out, which is judging by my experience in other associations a really high bar to clear.

In any case, such a decision can be review by civil court as well whether it actually met the conditions laid out in their charter.