Ten minutes later, I'm still trying to figure out the role of "thus" in this headline.

I think it’s clear from the “Motivation” section, as it’s actually preceded by another sentence there.

> Apple has transitioned its hardware products to the AArch64 processor architecture and is phasing out support for x64. Oracle engineers will thus stop maintaining the macOS/x64 port as of JDK 27.

The phrases is taken from the email. Apple stopped ... thus Oracle ...

I like it. Bring back thus as a normal word. Also thusly.

Also, having explained by example, finish with "quod erat demonstrandum"

It’s fine to have it as a normal word, it might even be one! Hehe it is to me at least :)

However, I believe OP is right, it’s un…grammatical? -parasable? in the headline? There’s no…referent?

More plain spoken :) - there’s nothing indicating what lead to the thus. I.e. “it’s raining thus I brought my umbrella”, we’re missing the “It’s raining” part