why did they choose to air this live?

For an internal team sure absolutely, but for public-facing work, prerecorded is the way to go

One of my internships was preparing Bill Gate's demo machines for CES. I setup custom machine images and ran through scripts to make sure everything went off w/o a hitch (I was doing just the demos for Tablet PC, each org presumably had their own team preparing the demos!)

Not doing it live would've been an embarrassment. I don't think the thought ever crossed anyone's mind, of course we'd do it live. Sure the machines were super customized, bare bones Windows installs stripped back to the minimum amount of software needed for just one demo, but at the end of the day it sure as hell was real software running up there on stage.

If it was pre-recorded we’d know it was staged and that assume they didn’t have a working product.

Their actual result was pretty bad, but, ya know, work in progress I guess.

Watch their big "Metaverse" presentation where its all vaporware and faked, presumably this is a cultural shift from that era.

The same unwarranted sense of confidence that tells them this product is worth making tells them that they can easily pull off a live demo. This is called "culture fit"