IIRC that's how they where able to defeat golems in web novel, no? Also
because of such training they lectured him since the ability to do so was too dangEROuS for the girls, as it allowed for "tools" to get vibrating functions... Some girls even felt such danger during training, no?
If they just showed a plain silhouette, I would've been worried for them next chapter. But, it definitely looks like she's a journalist and that look is just to mislead, so I'm imagining something hilarious will happen next time.
This story has stopped being "lonely attack" for a while now...MC definitely knows the way to the girls' heart by giving them clothes and let them let loose after a labryinth fight.