It doesn't actually target specifically males, just remember the mother from the previous chapter — she aged like everybody else.
Giorno thinks the enemy doesn't want to risk killing Trish, so he uses the Stand which will kill her guardians while barely affecting her. It seems his plan is different, though: Buccellati's gang must protect Trish at all costs, so if the enemy uses a Stand that affects everyone, the team has no choice but to fight him, and that reveals where they're hiding.