I mean, detonators generally only mean one thing. I feel the situation is different because literally everyone in that room is a superhero (Hero, being used here very, VERY loosely) but just whipping out something that everyone knows could blow something up is not a particularly intelligent idea, and people definitely are right to get a bit upset about it. Just my two cents. Plus I think Cordelia is just the type to be angry all the time anyway, so that definitely wont make her any happier.