On gravitational wave radiation and arrangement of galaxies post- big bang
When you go back in time, take collisions into account. A very highly elliptical orbit primarily leads to chunks colliding at the very first periapsis.

Even if they are not chunks but very dense and small objects (point-like), if you extrapolate back in time so far as to the straight line "orbit", what does it mean? Extreme case of objects with zero relative initial velocity going against each other on a collision course - ups, this "orbit" does not have a chance to "decay due to gravitational wave radiation". Two smaller chunks collide and form a larger chunk, which has now a non-zero velocity (probably, if the chunks weren't exactly equal momentum). The chunk won't enter a straight line "orbit" around (towards) anything, but either an elliptical or hyperbolic.

Your extrapolation does suggest that initial "chunks" hadn't ideally equal momenta (masses*velocities); that's all.