So confused. Isn't the U.S. still on DST until this Sunday, meaning the correct timezone at the Twitter HQ is in fact PDT (Pacific Daylight Time, UTC-7)? PST is Pacific Standard Time (UTC-8), i.e. "winter time".
Maybe they thought PST stands for Pacific Summer Time? Or this email was sent by someone from Europe, where DST ended last Sunday?
I’ve given up even trying and just use “PT” and “ET” or even “NYC time” or “SF time” especially when interacting with those outside the US (who are less familiar with the custom and more confused when a mistake is made).
CET in this informal way means "CET OR CEST depending on which of them is current at the location at the given time".
This can give rise to ambiguity in places, but it's pretty rare that it does.
I always want to correct people on it. But unfortunately it resides in a funky middle-ground between (a) corrections being welcome / helpful and (b) corrections seeming nit-picky / pedantic.
Similarly to misuses (according to classical grammar rules) of "who" vs. "whom".
Both grate on me, but there's no acceptable way to get others to change.