Doesn't this make the assumption that there is no more recent center of mass in some other direction and that the original big bang was symmetrical? Considering we are not yet clear what the mass of the universe consists of and where that mass lies, it appears that the assumption made with this graph would suggest, for example, an equal distribution of dark matter — apparently composing a very large part of the mass of the universe — yet we have discovered none in our neck of the woods.
I'm not suggesting that you're wrong, here, and the logic that you're proposing seems pleasing, but there seem to be some elements to be accounted for. Among other things, while the age of the earth may be about five Billion years, the universe itself is supposed to be somewhat older, twice to three times as old, as I understand it, unless there's more recent research that I'm unaware of.
The assumption that the original big bang caused a uniform distribution of matter through space may or may not prove true. I am inclined to think that space may well have been warped or folded by the original violence of the big bang and the nature of spacetime may have been warped and folded along with it, the boundaries being marked by membranes where the geometry of spacetime has essentially been crushed into itself. But that's all pure speculation on my part. Sort of reverberations of a large explosions within a trash compactor, echoing back and forth as the size of the trash compactor volume not so slowly expand. The initial reverberations would have set the basic shape within the first tiny fractions of a second, when there was time for the basic warping process to take place within a small enough space. Te tum te tum te tum.