For them to pull out it seems that associating with twitter harms their image, and that’s - according to them - related to moderation.
As for “proof” that twitter is more toxic;
> In the week leading up to Musk's acquisition, researchers said there were no more than 84 hostile tweets an hour on the platform. But from midnight on October 28 – the day Musk took ownership – to noon the next day, there were 4,778 hate-filled tweets. That accounts for more than 398 tweets an hour, about 4.7 times higher than the seven-day average leading up to that day. The potential reach for those tweets was more than 3 million, researchers found.
> Researchers also said there was an increase in negative sentiment, with more than 67% of the tweets sent after Musk's takeover having a negative tone.
https://www.cbsnews.com/news/elon-musk-twitter-caused-measur...