Gents,
Disregarding the vicious thug speak of Who's Ya Daddy for a minute, lets just think;
You can hold a practice drill at any time because, as has been pointed out, an emergency can happen at any time. However, if it is a planned practice during arrivals, it would make sense to have a skeleton crew to man the desk in the meantime.
That being the case, maybe it was a real fire - but that ain't what Approach was telling us.
Now getting back to Who's Ya Daddy, I just wonder whose your's is. I am trying to bring my kids up to be polite and kind. Your's seemingly couldn't manage it. You should be ashamed.