You have more sense to believe someone has to be able to see you to shoot you. Plenty of times people have been shot without the shooters knowledge that they were even there. But all it takes is one lucky (or unlucky) bullet to kill someone, even if they aren't seen.
Cover is different from concealment. Hiding behind a car door or under a pile of pine cones is concealment. Hiding in a freaking house would be cover AND concealment in my opinion < given the situation. Remeber, the stiatuion is a kid is outside aiming a rifle at you. Would a house be cover if we were hiding from an A-10? A pick up truck with a .50BMG machine gun? Probably not, but this isn't that scenario.
So with that in mind, Schlitz, (absolutely horrid choice of beer, btw) let's flip things around a bit. Put yourself in my shoes- same scenario, only Im standing downrange @ approx. 75m with a rifle/caliber of your choice, and a decent scope. Care to wager how far from that table and window you'd get before I got a couple of rounds into you? Now, if you had a firearm at hand in that situation- would you actually be trying to make a run for it? Or would you be considering getting that firearm ready-time permitting?
Bro, it doesn't matter if my AR is right next to the table, if I look up and you're already AIMED at me I'm hitting the deck. Once someone is already aiming at you, given this specific scenario, hitting the deck is your only option.
Now just because you've hit the deck that doesn't mean you stay in one spot, 09jusaac, because if they do start shooting they know where they saw you dropped. So you've got your whole house to crawl around to an even safer area while you dial 911 and remain armed incase this turns into a home invasion.
This is not just my opinion, it is common sense GIVEN THIS SPECIFIC SCENARIO. If you look out your window and see a squad of chinese infantry closing in on your home then sure, fire away and go down with the ship, but this is a kid outside 75m away already aimed at you ready to fire. Get down, call 911, and remain armed. Easy mode.