Since you apparently get the full $7500 regardless of how much your vacation costs, what he's effectively doing is docking everyone's pay $7500 if they don't take at least one fully disconnected vacation a year.
That's only true if their base salary/bonuses are $7500 below market, which I doubt is the case.
I'm not being pedantic and missing the point that you mean 'market average', because employment is not commodity purchase - so market average isn't meaningful unless you're painting with very, very broad strokes.