Not the op, the gp, or even the parent, but I'd like to say that while I'm certainly not condoning flashbangs in cribs or saying that "grenade" is technically inaccurate in the original sentence, there is a very different mental picture when someone says "grenade" vs "stun grenade". I feel like in an era where it's easier and more prolific to crucify a person because of their words than in the known history of mankind, the distinction between "grenade" and "stun grenade" should be made.

Does that make this okay? No. Not even a little. But let's err on the side of clearer communication.

Exactly. It's akin to the difference between dropping "a bomb" and dropping "a nuke". The terms are sometimes interchangeable but should never be confused.