This is a classic example of making the perfect the enemy of the good.
Instead we should discuss why these are not implemented and how could be proceed to implement them.
If you want to discuss how a follow-on from Signal could and maybe should address some or all of those points, great! That's a conversation worth having. But it doesn't sound from your toplevel comment as though it is the conversation you're trying to start.
This is mis-categorisation. The article says "I won't recommend the use of Signal" and gives reasons and desired improvements.
I think that you are misinterpreting the articles intention. It is more complex than a single statement. I believe that the author wants Signal to change in certain direction. It is hard to do when the userbase is growing regardless and people are not aware of the issues.