Intolerance is only an issue when it is equated with violence. There's no real issue or paradox of intolerance if you equate intolerance with asserting boundaries nonviolently - this is the literal basis of unconditional love.

The applicable law is Article 21 GG:

1. Political parties shall participate in the formation of the political will of the people. They may be freely established. Their internal organisation must conform to democratic principles. They must publicly account for their assets and for the sources and use of their funds.

2. Parties that, by reason of their aims or the behaviour of their adherents, seek to undermine or abolish the free democratic basic order or to endanger the existence of the Federal Republic of Germany shall be unconstitutional.

3. Parties that, by reason of their aims or the behaviour of their adherents, are oriented towards an undermining or abolition of the free democratic basic order or an endangerment of the existence of the Federal Republic of Germany shall be excluded from state financing. If such exclusion is determined, any favourable fiscal treatment of these parties and of payments made to those parties shall cease.

4. The Federal Constitutional Court shall rule on the question of unconstitutionality within the meaning of paragraph (2) of this Article and on exclusion from state financing within the meaning of paragraph (3).

5. Details shall be regulated by federal laws.

Key point here is "seek to undermine or abolish the free and democratic basic order", quoth the BVerfG:

The free democratic basic order can be defined as an order which excludes any form of tyranny or arbitrariness and represents a governmental system under a rule of law, based upon self-determination of the people as expressed by the will of the existing majority and upon freedom and equality. The fundamental principles of this order include at least: respect for the human rights given concrete form in the Basic Law, in particular for the right of a person to life and free development; popular sovereignty; separation of powers; responsibility of government; lawfulness of administration; independence of the judiciary; the multi-party principle; and equality of opportunities for all political parties.

It's their own definition so push come to shove they're going to add to it. Overall though the lines aren't new and haven't shifted, that's a quote from a judgement from 1952.

Paragraph 3 is new, that has been introduced after banning the NPD (now "Die Heimat") failed not because they would not be opposed to the free and democratic order, but because they were judged to be too impotent to do anything about it. Previously banned parties include the NSDAP, not under this law but by the allies, then the SRP as it was a successor of the NSDAP, and then the KPD not for being communist but for being run by the KGB and laying siege to parliament. Bans of the FAP and NL failed because the BVerfG said they're not parties so they were banned as associations, instead. Last case is the NPD, the first attempt failed because the state had so many moles inside that the court saw itself unable to distinguish between state and party actions, the second as already said because they're yes, hateful assclowns, but also pathetic. They've been excluded from state funds for six years, the case will have to be judged anew in 2030.