I think that assumes the Galaxy formation was God’s design, or maybe something much denser and he just spun it to begin scattering stars. But that would run up against all of the irregular shaped galaxies that do not take this form, or which have had events happen that take longer than 6,000 years.

Things like collisions that tear apart galaxies and reform them into new shapes. This requires a gravity interaction, and stars that were just slowly moving outward at a pace of {this far}/6000 years would just scatter like pool balls. Or more likely, nothing would happen at all, because galaxies are mostly empty space. In a galactic collision, most of the stars just pass by each other without contact. Nothing to stop the initial outward fling.

If we accept gravity is a force pulling things together, and that these stars have an initial outward momentum that is working against it, we have to assume the outward momentum is much stronger than gravity to keep the normal galaxies from collapsing. But gravity has to be stronger than the outward momentum to recombine collided galaxies into different shapes.