I can see the posts just fine (albeit with JS enabled), but not the replies and subsequent conversations. Assuming you were referring to the latter, then yes I'd agree with you.

Sometimes when I load Twitter, even to view a single, it requires sign in.

I don't know why it sometimes does and sometimes doesn't.

I've noticed the same and it's really frustrating, it just straight up redirects to the login page sometimes. I guess I'll have to accept the fact that it's closing down, visitors are not welcome. Can't view a single post or picture in the future but so be it.