Google doesn’t have a monopoly in workspace applications.

You don't have to have a monopoly to be monopolistic.

The Sherman Act says that any action by an individual, or conspiracy of a group of individuals, to "restrain trade" or seek a monopoly is illegal.

Monopolies aren't a prerequisite for antitrust action, they're the failure state when you should have acted sooner.

I doubt Microsoft would qualify as a monopoly under present-day excuses being made for Google yet here we are with Internet Explorer Part Deux.