Yea he blamed it on antitrust lawsuit and said that Microsoft lost $400bn because of missed mobile OS opportunity or in another words because Android beat Microsoft and its Windows Mobile/Phone.
But that still really would be the antitrust suits themselves since 1) MS got themselves into that mess in the first place and 2) Bill Gates shouldn't have let it distract him so much from potentially vital projects. 3) employee accounts of the internal politics at the time pretty much meant that most new products were doomed to fail from the outset if management on the Windows teams thought they were even the least bit of threat to them.
Gates even admitted he messed it up and lost $400bn with mobile operating system. https://youtu.be/W5g4sPi1wd4?t=709
There is a different story/side to this statement.