Ah, the "defense from douchebags" trope. It's timeless, and typically "harmless" thematically. Though to be fair, it's application has an incredibly wide range, from very brief and minor, to near rape/death... Personally, if the usage matches the "tone" of the manga, or contributes significantly (tends to happen with the more extreme end of the range), the overly cliche nature doesn't bother me. It's a LITTLE random here, but it's purpose seems relatively transparent.
As ever, thank you for scanlating.