Doesn't it seem entirely wrong that the BIOS has any idea about O/S's to start with?

Completely the wrong way around.

Not only that, but to specifically test for an OS that supposedly they don't care about and give it crap data?!

More like, they don't care about it, and accidentally forgot to update a table entry.

This is why Linux lies and says it's Windows to ACPI. I strongly doubt that it's malicious, they just don't care enough to test it and keep it up to date with Linux, so stuff breaks.

Sure. So it'd be like finding this in a Windows Vista system call...

if (appName.equals("firefox")) { sleep(60); addSomeBugs(); }

MS has a history of doing this sort of stuff. For example, they deliberately fed Opera browsers broken CSS files: http://people.opera.com/howcome/2003/2/msn/

Therefore, MSN looks for "Opera" in the User-Agent string and purposely sends Opera7 a style sheet which distort pages.

They caused quite a stir when they broke kerberos too.

I don't think Garrett works for/with ubuntu for some time. See even the tags in the blog.