Death of the Author is just one more tool among many you should wield when analyzing a work. It is not the be-all and end-all. It can be misused. And this is one of the cases of misuse.

It's like when the author writes that the curtains are blue because he thinks it's a cool color. Then people theorize that the color "blue" symbolizes depression, and when the author comes and dispels this, they invalidate the author's intentions. This is not a good application of "Death of the Author".

It takes a lot of modesty to claim that the curtains are blue. You'd have to admit that when you personally interact with the work, you feel that the curtain's color reinforce the feeling of dread and depression in the story. Now that's a good application of "Death of the Author".

But to claim that the author symbolizes depression with the color blue would be objectively wrong. And people try to get around this by saying not that "the author symbolizes..." but rather that "the story symbolizes..." as if the story, a combination of words, had sentience and agency.

There are only two sentient agents. The author, and you (the reader). Any interpretation must be the product of the voluntary effort of one of these two agents.

This thread is a combination of bad applications of "Death of the Author". The scenes in Evangelion may be interpreted as materializations of complex philosophical concepts (just like any story), but it must be made clear that the author has no background on philosophy, did not write the story with philosophy in mind and did not consciously inject any philosophy in it. The reader is free to experience the story however they want, of course.