Nope, it says that the upgrade requires a 3 GB download.
10.0.240 is not the upgrade - that has also been explicit stated by MS. Couldn't find Abe's tweet, so this will have to suffice
It says nothing about GWX - which is downloading bits for the upgrade.
It also says nothing about a lot of things, whether the moon is made of cheese or not.
The thing people need to keep in mind is that the production release is different from the Insider releases. While the code will match for a short period of time, they are governed by different licenses, EULA, and terms of privacy.
I'm sure you've seen this flow chart that someone smarter than me took the time to work up.
Attachment 26186
Notice that if you installed a Preview release on top of a valid OS, you'll get the the upgrade.
Is it official from MS, nope.
So here's something official:
Source
This is very clear and adds a bit of "Oh man did I have that wrong". The key is and always has been a qualifying OS.
The only way an Insider release becomes a production release is if you opt-out of the Insider program - otherwise the Win10 release that insiders get that matches the production release is, and I quote
just another build for Insiders, and those who stay in the program will simply get the next (sic Insider) build after as well.
One of the confusing points is "What about people multi-booting with a clean install of an Insider release". I don't know, other than for a short time the Insider release will be equivalent to the production release .. but again it's just another Insider build subject to the next development Insider build. An interesting side effect of 10.0.240 is that when I installed it, the OS was licensed to my local account on my Win8.1 install, it was a Retail license, but the key was the Insider build key. I'll be interested in seeing what slimgr.vbs tells me about the next Insider build (which should equal the production build)
I expect that the next Insider build after matching the production code will come rather quickly so that production code and development code do not match for very long.
Buldfeed shows that 10.0.10508 is the highest numbered release being worked on - probably not the next one offered, but there's a lot of work going on past 10.0.10240.
Anyway..... if you read all of that you're crazier than I am