That guy's style guide seems to conflict with the Cambridge editorial services guidelines - though that is for
books rather than papers:
> Spaced en rules (or ‘en dashes’) must be used for parenthetical dashes. Hyphens or em rules
(‘em dashes’) will not be accepted for either UK or US style books. En rules (–) are longer than
hyphens (-) but shorter than em rules (—).
Section 2.1, "Editorial services style guide for academic books" https://www.cambridge.org/authorhub/resources/publishing-gui...