Just an add on : Wittgenstein's quote makes me think of this famous dictum of Epicurus according to which
“Why should I fear death?
If I am, then death is not.
If Death is, then I am not.
Why should I fear that which can only exist when I do not?
Long time men lay oppressed with slavish fear.
Religious tyranny did domineer.
At length the mighty one of ...
The OP mentions the influence of Schopenhauer and of Moore on Wittgenstein. Yet another influence on Wittgenstein, which is even more relevant to the aspects of the Tractatus asked about, is David Hume. Semantic atomism, the non-existence of the self, the is-ought gap, the lack of objective necessity, the problem of induction, all take part in the Tractatus.