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 critical point which is being made is that the Pr0gramm users donating to cancer research and the Pr0gramm users mining through Coinhive might be different people, and lumping them together because they all use Pr0gramm would be unfair (this is the argument they're making--I don't know whether it's true).

I think you misunderstood something. Pr0gramm users can use something like coinhive voluntarily, on their own machine only, unless they like blasting their login data out into the internet. This can be used to get premium time for this pr0gramm account and nothing else.

The connection here is, that this was the prototype for what is now coinhive, which has been developed by the former pr0gramm admin.

This is the connection between pr0gramm and coinhive. I don't think anyone ever claimed (not even Krebs) a lot of pr0gramm users would be involved in blackhat usage of coinhive. It's an imageboard with thousands of users. I mean, seriously, the amout of people on HN proportionally that use coinhive in a blackhat way is probably higher than on pr0gramm. Simply because most people here have the technical skill to do it, where pr0gramm is simply a website for shitposting.