They are trying to gain access to financial information, and also they are compromising not only the companies but all the third parties, like lawyers, that are helping that company.
Likeallparties, the Greens tend to change their tune when they get closer to power, just as they did when they went into coalition with the SPD in the federal government of 1998.
Of course, what all the parties would really like is the promise of state funding, so they didn't have to grub around for donations from people who might want something in return.