I don't think that they assumed that all the attendees will be male, they only assumed that most of them will. Similarly, they didn't assume that everybody like

I don't think that they assumed that all the attendees will be male, they only assumed that most of them will. Similarly, they didn't assume that everybody likes house music ( or whatever genre of music "Live DJ - Let great beats get you in the groove" refers to ) or dark chocolate, they just assumed most people do.