> "Tweets" are much longer, so it no longer feels like microblogging. Sensitive content feels even dumber, I don't want to click "Read more" in order to view a tweet like it was some kind of a ad-bait blog post.

While messages can be longer, IME they tend to be about Tweet length.

Content Warnings are optional and can be expanded automatically by your client.

> And I have no idea if I chose the right Mastodon instance with the right hall admins that won't read my private messages and ban me for having the wrong opinion.

Valid. But I'm not sure this is much different at Twitter. And at least with Mastodon, you can leave and take your data with you. If you're concerned about this, you have the option of hosting yourself. I know a lot of people rankle at that suggestion but Twitter doesn't even give you that option.