The users of the platform are not the people who include Coinhive on hacked websites. Pr0gramm simply allowed its users to voluntarily mine in their browsers and be rewarded with a premium account. The main benefit of a premium account is, that no ads are shown on the site.
The thing is, Pr0gramm users are not the people that add Coinhive scripts to hacked websites.
Before Coinhive was launched, users on Pr0gramm were able to activate mining and be rewarded with a premium account on the site. They weren't even forced to do so but were able to opt-in voluntarily.
So the relation between Coinhive and Pr0gramm merely is, that the people behind each website know each other and used Pr0gramm as a testbed for Coinhive before it became publicly available.
The word "Krebs" in German translates to crab as well as cancer.
They are donating to the charities that work against cancer and are commenting "Krebs ist scheiße" which would translate to "Cancer is shit" as well as "[Brian ]Krebs is shit".