QUIC was a mistake on the roadmap. I've removed it. I mis-understood some documentation about experiments with QUIC. Sorry for the confusion.
I'm not sure how you come to this conclusion, or what you mean? As I understand it, QUIC is a transport layer for the HTTP application-level protocol, so I would guess that pretty much all of the JS-exposed APIs are equally applicable.
I guess they mean extra API that utilize stuff that's in HTTP/2 but not in HTTP/1.1.
Why focus on QUIC when the JS APIs to use it aren't available? Numerous of the features of HTTP/2 aren't usable (i.e. trailers, flow control, security sensitive headers, priority, etc.).
I don't understand how the web is supposed to flourish without giving web developers some kind of access to these tools. Meanwhile, app developers are showered with such goodies.