It's sneaky, it behaves badly and counter to the user's interests, and because it's a compiler, it propagates that bad behavior (though not in a self-reproducing viral fashion). It's fairly mild on the scale of malware—I'd rank it slightly less bad than adware, but roughly on par with AV software that deletes any tools it deems to be for piracy purposes.

I call stealing your customers cpu cycles without permission for marketing purposes malware. If you don't that's ok. We can disagree.

I literally posted the definition of malware. Where is it gaining unauthorized access?

It says 'or'.

If it disrupts, that fits the definition you gave.

Or do you think a trojan that deletes your boot sector isn't malware?

Your definition isn't the only reasonable way to define the term, and you seem to be parsing it incorrectly anyways.

Seems pretty disruptive to my layman eyes to force code to run slower on a competitors hardware.

Oh for sure. I’m quibbling over the use of the word “malware”