That’s not really what I’d call a “WWDC talk”, but sure, it mentions that Apple won’t provide Boot Camp, and that they are running their OS demos using virtualization. I didn’t see a claim that they won’t let you reduce the boot security.

"We're not direct booting an alternate operating system, it's purely virtualization. Hypervisors can be very efficient, so the need to direct boot shouldn't really be a concern."

For me that quote means that they're not allowing booting any alternate operating system and they expect developers to use virtualization if other operating system is needed. I would be happy to be wrong about that.

I understood that as "we weren't booting something else in our demos, we were using virtualization" but not "we can't boot anything else". I am sure, however, that they would like you to use virtualization instead of direct booting.