Is it because the Koch is considered evil by the left while Soros is a saint?
Seriously, did you even read the article? (I know, I know, this is
Koch is the subject because an earlier article, by the same author, had listed Koch as one of nearly 600 people who appeared to have exceeded campaign contribution limits. Turns out this was incorrect - an error due in large part to the disasterously poor state of data on contributions by major donors. The whole damned article is both exonerating Koch and explaining where the original analyis went wrong. It's about Koch because Koch's company took the time to contact the author, work with him to identify where and how some of the erroneous data came about, and help set the record straight. If one of the other nearly 600 donors listed had done the same, this follow-up article might easily have been about someone other than Koch.
It's got nothing to do with "evil", "good", "bad", etc, except inasmuch as the FEC data is manifestly "bad", and woefully inadequate for even the FEC themselves to determine who may be breaking campaign finance laws. If you want to get upset about the article, get upset about the real point - that nobody has sufficient information to tell whether major contributors on either side of the political aisle are breaking the law. (And there were plenty of Dem donors in the original article if you take the time to read it. I apologize in advance to you that Soros wasn't on the list. Well, that's not true - there's two Soroses (Sori?) on the lists - just that <Jedi>these are not the Soroses you're looking for</Jedi>)
So untwist your knickers, grab a beer, chill out, then try actually reading the article.