The linked article correctly uses "British" to denote the style of punctuation, I do not understand why OP decided to use "English" which implies that people in Scotland and Northern Ireland might punctuate differently.
Not sure about the author, but for several countries "English" is colloqualy used as a stand-in for British in general (and England for the UK), as those were the British they most commonly met.
Doesn't matter, language follows use, not etymology or geography. If a term has been established as something (in actual use) then it will be used, doesn't matter if it's not technically correct (same way "Indians" was used for centuries for Native Americans, and only fell out of use because of political concerns, not because it was also obviously incorrect and based on a misunderstanding of a whole continent).
edit: for the record, I wrote the article and also posted it here. so I figured I could take the liberty of changing the title when sharing here.