It's unclear as to why. As you can see below, the tweet includes a video which works backwards through the versions of Windows until it reaches Windows 1.0 released back in 1985. The text reads, ...
Members of the Windows 1.0 team at their 40-year reunion this week. L-R, kneeling/sitting: Joe Barello, Ed Mills, Tandy Trower, Mark Cliggett, Steve Ballmer (holding a Windows 1.0 screenshot) and Don ...