So why is he leaving Microsoft out of the mix? He claims Google having an 88% share in advertising is a monopoly, why then claim that Microsoft is not a monopo

So why is he leaving Microsoft out of the mix? He claims Google having an 88% share in advertising is a monopoly, why then claim that Microsoft is not a monopoly when it has a similar share of the PC space? He says that Microsoft competes in the market with many players, but Google also competes in the market with many players.