I can't speak for anyone else, but here are my thoughts.Elon said his last sale was insurance in case he needed more for the Twitter purchase and that he wasn't planning to sell more.
Why are so many people here convinced he is going to sell more?
When he mentioned his last sale was insurance, that was before he agreed to the full $54.20 price. That was also before all of the information about how bad of shape Twitter was in came to light.
So, higher purchase price than might have been predicted at the time, combined with the obvious viewpoint (pointed out directly by Elon) that it's over-priced, makes me question just how many equity investors might pull out. What if all of them pulled out? Did Elon's last sale anticipate this? We have heard that he is asking around for more equity investors to join.
I'm not convinced he is going to sell more; it's very possible he has the funds needed. But I'm also not convinced that he isn't. I believe many others share this uncertainty, which is one of the overhangs that are weighing on TSLA.
Elon has had many opportunities to refute those who are suggesting he needs to sell more. Dave Lee and others have asked him directly on Twitter. He has not done so. I thought it might be because he was in the quiet period, but that's not the case anymore. The longer he stays silent, the more uncertain I become.
As you say, his last comment was he wasn't planning to sell more. But plans can and do change all the time.
EDIT: ninja'ed by @WilliamInPhx, who stated my thoughts much more succinctly.