"Yeah, because they explode into monsters before you can." Or shatter, but it's trying to make a point. Not because it's mad that it was taken along. It just has a lot of complicated feelings about how easily Levi and the others (?) seem to have decided that the risk was worth it, and it's easier to be angry, as ART once put it. (Shut up, ART.)

But it's a stupid thing to fight about, because it's not like they can go back and abandon it, and it's not like SecUnit particularly wants to be abandoned. So instead, it just says, "Fine."