The Fascists equated gay sex with antifascism. Apparently.

Quoting Gabriella Romano’s The Pathologisation of Homosexuality in Fascist Italy: The Case of ‘G’, page 29:

Virility, [George L.] Mosse argued, became a national symbol during the régime, embodied by the dictator’s himself, his physique, his behaviour and way of addressing the crowds, his gestures; dandyism, weakness, effeminacy were perceived as anything that stood in the way, anything that was anti-Mussolini and his ideology.

Furthermore, as the régime concentrated on demographic campaigns, homosexuality came to be perceived as sterile and therefore essentially anti-fascist and selfish, against what was good for the nation. The New Italian Man’s actions were to be inspired by his love for the country: private life was considered a responsible act towards the nation, sexuality had to be aimed at procreation.