I can't imagine anyone with half a brain not figuring that one out.
Get real, there is an active shooter and what? Someone is standing around with musket aiming it? Are you serious? I'm not even kidding, what sort of bizzaro situation are you envisioning where a terrorist is shooting people with a real gun and there is someone holding up a toy and hanging out next to them?
What sort of idiots do you imagine are going to be responding and see that and think, "hey lets shoot the 5 year old?" Again, setting aside how absurd it would be to have the individual hanging out there "aiming" it.
Have you even seen these "replicas" you speak of?
As to the "a week ago you could have". You say that as if it couldn't have happened today, it could have. Even if they put everyone through the detectors.
Anyway, fantasy land is an area in MK, it's not a real place and these fantasies some people are having about toy pop guns or buzz blasters or bubble guns, let alone what would actually happen in an active murderer scenario are so far fetched, they wouldn't even make a B list movie.
These things would be like me telling NASA how to build the next international space station... I shouldn't be telling them anything because I'm clueless about, aside from watching a few movies. No different when it comes to the current security situation and seeing some of the replies in this thread, clueless people having to invent impossible scenarios to justify how something that does nothing to improve safety, somehow makes them feel safer.