They let like 2 Nazis on, taking the viewpoint basically (1) it's in the spirit of the 1st amendment to allow even reprehensible speech (2) guys it's like 2 of them and the number of people reading and being convinced by them is likely to be 0
And the entirety of the knee-jerk fediverse politics community saw an opportunity to take a pointless stand on something, and in their eyes shone the promise of being able to make some smug self-important postings about how something good is actually really problematic and you're just not enlightened enough if you don't agree
And now Substack is literally Hitler even though it was doing a whole bunch of great things, outside of the 2 Nazis