> Also, I don’t see any use in saying someone shouldn’t be angry or anxious in a particular situation.

If you make a statement like that, I will have to ask you to reread the article. He's clear in saying:

1. Anger and anxiety should not be conflated.

2. Anxiety is OK.

> You can’t control your emotions like that.

The thesis (by him and other sources I've read) is that anger is an emotion that you do create (most of the time). It's a result of a narrative coupled with another emotion (anxiety in this case). You can't control the anxiety. You can control the narrative in your brain. With certain narratives, you get anger. With others, you don't.

I've known many who've made that journey. It seems the author has as well.

Now if your argument is that it's OK to be angry (you've made the narrative clear in your comment), I won't disagree.