Kolbe center, from what I have gathered, are geocentric. They believe the earth is a sphere that is fixed in the center of the universe and does not move. That may be why they go after flat earthers.
My understanding is that the Kolbe center is run by mostly protestants. Sungenis fits in with the prots because he's a hardcore, pro-new-rome, indulter.
Both Prots and hardcore indulters suffer from the same philosophical error, which affects their thinking on a variety of topics (i.e. religion, politics, culture, etc). Fundamentally (pun intended) prots believe that the "centrist" position is the best way for society to operate. So they gravitate towards a "moderate" approach in all things.
1. Heliocentrism is wrong; flat earth is extreme; the best approach is geocentrism.
2. Atheism is wrong; Catholic Church is extreme; the best approach is protestantism/love-God-in-your-own-way.
3. V2 is wrong; Traditional catholicism is extreme; the best approach is indultism/fighting-for-the-church-from-the-inside.
Each of topics (and there are many more examples) suffers from a false dichotomy. They falsely label the extremes, to arrive at their desired "middle ground". Their core error is to define truth based on "the most popular opinion of the day, which most people agree on", then they work backwards to falsely define the extremes, to support their "popular, centrist" solution.
In our day and age, society is so far left/sinful, that the Truth does *seem* extreme, but it's not so.