Insiders see this style of Upgrade on a regular basis (with each new major Insider Build). Microsoft just made a big blog post about a new system for this style of Upgrade (the "Universal Patch Platform") and has asked Insiders to keep an eye out on it. A White Hat attempting responsible disclosure could at least check on Insider Builds and attempt to provide feedback on the new platform through official channels.
Publishing early just damages your relationship with the company, the community, and makes it more well known that you _don't_ have good intentions.