If a weapon is un-attended on a counter you follow rule one; Treat every gun as if it were loaded.
Obviously the article has some holes that will most likely never be fleshed out. Even though the general public is not in the know on firearms I'd guess that call was made to the police as a result of a conflict with the tenant. Since none of us were there we can't say for sure what went down but the most logical step would be that this was not a call made for the good of the community but a stab in the back. Maybe deserved, maybe not.
Once the police were there and had verified it was only a toy they would have quizzed the tenant somewhat along these lines. Why do you have that? No reason. What are you going to do with it? Nothing, it's just there. After that type of exchange they'd have suggested that they take it along to prevent another false alarm.
I don't think the point of this thread should be to discuss the right and wrong of the police or society's phobia of weapons. There's thread after thread of that already on here.
I think we should keep this on topic of reasonable steps that members here can take to store and transport their gear so they are not on the receiving end of a situation like this.
Airsoft, where nothing is hurt but feelings.