When someone is pulling out a non-gun (eg wallet) and gets shot, there is considerable controversy. See the relatively recent case in NYC.

When a kid pulls out a toy gun and gets shot, it is a sad note on the local news, nothing more. My awareness of this is because it happened a few years ago in Vancouver. There was some local publicity, there were pictures of the "gun" in question, and there was the usual sad litany of experts telling parents to consider carefully what toys they bought their kids.

I don't remember whether a lawsuit was brought. If so, it was dismissed. After all when on close visual inspection it was impossible to tell that the gun was not real, the reactions of an officer when a kid pointed it at him and cried out something like, "I've got you now!" were perfectly understandable. (I know that said officer was visiting a private home. I don't remember whether he was serving a warrant or not.)

Cheers,
Ben