"I have no clue who this Malleus is." No, Vegeta, don't say that, you don't know what you've just started.

Really, he had done it mostly out of just reaction, focused on making sure the guns were still all safe enough to be set up somewhere until Cassie or someone with similar knowledge of them came back in to check on them. And for them to get all the shelving back up. It's an annoyance, he had came to train or observe and see what others were capable of, not dealing with someone's temper tantrum.