First, it doesn't explain Fermi's Paradox, it merely adds another term to it. In all of those various probabilities, apparently there is something like a 10% chance of not getting taken out by a gamma burst in half-a-billion years. I would also expect the odds to get better as a given galaxy "settles down", generating fewer big, hot stars and more smaller, calmer ones. Some neighborhoods are probably rougher too. I wouldn't wait around to settle Trantor, near the center of our galaxy.
Second, I wouldn't consider intergalactic contact in any serious way - the distances are bad enough for interstellar, do we really want to add a few more orders of magnitude?
Third, our presence establishes our galaxy as one of the more benign ones. There is at least one neighborhood that has been sufficiently peaceful for the last half-billion hears. Last I knew, there were no supernova candidates close enough to cause that kind of trouble any time soon, either.
Fourth, I'll focus on your word "silliness", which I think you meant as an understatement. There is conceivably a chance that we are under observation, and rank as "too silly" for any contact. The Earth has had an oxygen atmosphere for the last half-billion years, and we're on the verge of being able to detect other such atmospheres on other worlds such as Kepler has found. It's not a bad assumption that any civilization capable of interstellar travel is also better at planetary surveys than us. If they're there and within a few thousand light-years, they know something worth seeing is probably here.
At this point in physics we're stuck at the Standard Model. We have many theories that move beyond, but no facts to select among them, and many of the experiments would be incredibly expensive. But let's say one day we saw a "warp signature", it's quite possible that we could immediately discard half of those theories. (By "warp signature" I really mean physical evidence of truly advanced technology.) IF there were here watching us, and seeing our "silliness" as well as the scientific acumen of some, they would be especially careful that we see no such evidence.