[twtw]

The explanation in that paragraph is not necessarily incorrect, just confusing because it talks about voltage "in" wires and isn't clear about what two terminals are being referenced.

It is true that the voltage between live and neutral changes sign, so neutral is sometimes 170V above live. But neutral is almost always at ground, and live goes to -170V relative to ground.

That last paragraph though seems wrong, so OP may have been confused himself when writing.