Is it any of our business? Not even a little bit.
But since we are discussing them - the OP is right. Was it his place to opine on her modesty issues? No, hence everyone jumping on his back.
But seriously? Those shorts are not even on the borderline of modest and I think any reasonable LDS woman would tell you that. We all know what we were taught in Young Women's and in reading For the Strength of Youth and those shorts are way too short.
Any girl that says those are modest is delusional. But it's her choice. Either way, it's an individual choice, not ours, and shouldn't be up for discussion in the first place (and I know, I'm a hypocrite for discussing them!!)