The blog posts mention that releasing it today is a shot across the bow for Enterprise. Given Enterprises like their year+ efforts to "test" software before ever deploying it, they want Enterprise to start that process today, ahead of 20H1 when all consumers presumably will be pushed to it.
It's also a very subtle signal for several reasons to release it the day after Extended Support for Windows 7 ended. On the one hand, it supports Windows 7, so there is a possible mixed message there, which is why it is subtle. On the other hand, some of these Enterprises should realize that the last time the browser team at Microsoft did a release like this after/ahead of a Windows EOL they highly revised their browser security support policy. (Back with IE11 adding support for a couple older versions of Windows and Microsoft immediately dropping support for IE <11, despite earlier "bundled with Windows support timeframe" promises.) It can be seen as a very subtle "IE is dead, move on from it, already, you dinosaur customers".